WO2008107701A1

WO2008107701A1 - Diagnosing psychotic disorders

Info

Publication number: WO2008107701A1
Application number: PCT/GB2008/000831
Authority: WO
Inventors: Sabine Bahn; Rachel Marie Craddock; Marlis Herberth; Natalia Gorota Krzyston
Original assignee: Cambridge Enterprise Limited
Priority date: 2007-03-08
Filing date: 2008-03-10
Publication date: 2008-09-12
Also published as: GB0704515D0

Abstract

A method of diagnosing, predicting or monitoring a psychotic disorder in a subject, which comprises contacting a test sample from the subject with healthy T-cells, and assessing the response of the T-cells.

Description

DIAGNOSING PSYCHOTIC DISORDERS Field of the Invention

The invention relates to methods for diagnosing or monitoring psychotic disorders, in particular schizophrenic disorders, using a T-cell based assay and biomarkers. The invention also relates to methods for identifying biomarkers incorporating a T-cell stimulation assay. Furthermore, the invention relates to methods for identifying agents useful in the treatment of psychotic disorders. Background of the Invention

Psychosis is a symptom of severe mental illness. Although it is not exclusively linked to any particular psychological or physical state, it is particularly associated with schizophrenia, bipolar disorder (manic depression) and severe clinical depression. These conditions, their characterisation and categorisation, including DSM IV diagnosis criteria, are described in WO2007/045865, the content of which is incorporated herein by reference. WO01/63295 describes methods and compositions for screening, diagnosis and determining prognosis of neuropsychiatric or neurological conditions (including bipolar affective disorder, schizophrenia and vascular dementia), for monitoring the effectiveness of treatment in these conditions, and for use in drug development. Techniques such as magnetic resonance imaging or positron emission tomography, based on subtle changes of the frontal and temporal lobes and the basal ganglia, are of little value for the diagnosis, treatment or prognosis of schizophrenic disorders in individual patients, since the absolute size of these reported differences between individuals with schizophrenia and normal comparison subjects has been generally small, with notable overlap between the two groups. The role of these neuroimaging techniques is restricted largely to the exclusion of other conditions which may be accompanied by schizophrenic symptoms, such as brain tumours or haemorrhages. The validation of biomarkers that can detect early changes specifically correlated to reversal or progression of mental disorders is essential for monitoring and optimising interventions. Used as predictors, these biomarkers can help to identify high-risk individuals and disease sub-groups that may serve as target populations for chemo-intervention trials; as surrogate endpoints, biomarkers have the potential for assessing the efficacy and cost-effectiveness of preventative interventions at a speed which is not possible at present when the incidence of manifest mental disorder is used as the endpoint.

A need exists to identify sensitive and specific methods and biomarkers for diagnosis and for monitoring psychotic disorders, such as schizophrenic or bipolar disorders. Additionally, there is a clear need for methods, models, tests and tools for identification and assessment of existing and new therapeutic agents for the treatment of these disorders and methods for diagnosing psychotic disease.

T-cells are lymphocytes which develop in the thymus and play an important role in the immune system. There are two sub-populations of T-cells: cells with a CD4 marker are called helper T-cells, whilst CD8+ cells are cytotoxic T-cells. Both T-cell types have a T-cell receptor (TCR) for antigen recognition. Stimulation or activation of a resting T-cell is initiated by the interaction of the TCR-CD3 complex with antigen-MHC class Il molecules on the surface of an antigen-presenting cell. This interaction initiates a cascade of biochemical events in the T-cell, including activation of gene transcription that eventually results in growth, proliferation and differentiation of the T-cell.

WO2007/063333 (unpublished at the first filing date of the present invention, the content of which is incorporated herein by reference) discloses that assays, conducted on stimulated or unstimulated T-cells, can provide valuable information on the condition of a subject. In particular, assessing a response to stimulation in a test T-cell sample method can be utilised in assessing prognosis of a psychotic disorder. T-cells provide a good model in which to investigate cellular function, as they are relatively easy to isolate with high purity, e.g. from peripheral blood, and can be obtained in a minimally invasive fashion. Summary of the Invention

The present invention is based on the finding that serum from schizophrenia patients shows a reaction with healthy T-cells. An aspect of this invention is a method of diagnosing, predicting or monitoring a psychotic disorder in a subject, by assessing the interaction between a sample from a subject and healthy T-cells. The T-cells are preferably stimulated. Description of Preferred Embodiments

For the avoidance of doubt, terms such as "response", "control" and "sample" as used herein include the possibility of there being more than one such response, control or sample, respectively. The term "diagnosis" as used herein encompasses identification, confirmation, and/or characterisation of a psychotic disorder, in particular a schizophrenic disorder, bipolar disorder, related psychotic disorder, or predisposition thereto. By predisposition it is meant that a subject does not currently present with the disorder, but is liable to be affected by the disorder in time.

Monitoring methods of the invention can be used to monitor onset, progression, stabilisation, amelioration and/or remission of a psychotic disorder.

The term "psychotic disorder" as used herein refers to a disorder in which psychosis is a recognised symptom, this includes neuropsychiatric (psychotic depression and other psychotic episodes) and neurodevelopmental disorders (especially autistic spectrum disorders), neurodegenerative disorders, depression, mania, and in particular, schizophrenic disorders (paranoid, catatonic, disorganized, undifferentiated and residual schizophrenia) and bipolar disorders. Preferably, the invention relates to schizophrenic disorders. T-cell samples are preferably obtained from peripheral blood taken from a subject. Preferably, T-cell samples are freshly isolated, that is they are used immediately following sample collection.

An example of a method for T-cell isolation is described in Example 1 of WO2007/063333. However, the skilled person will appreciate that other methods known in the art for obtaining or isolating T-cells from a biological sample, such as peripheral blood, may also be employed.

The term "stimulus" as used herein refers to a stimulus capable of inducing a response, preferably T-cell proliferation and responses associated with T-cell receptor-triggering. In vitro T-cell stimulation may be used as a method of comparing the functional responses of patient and control cells, firstly in order to investigate peripheral evidence of disease processes in schizophrenia and also to investigate whether global abnormalities or deficits in cell processes, such as cell signalling, gene transcription, protein synthesis and trafficking underlie the pathophysiology of this disorder. In vivo T-cell activation involves ligation of the T-cell receptor (TCR) through interaction with specific antigen presented in association with MHC. The TCR signalling complex is composed of a number of molecules including CD3, which provides the cytoplasmic signalling function of the complex, CD45, involved in de- phosphorylation of inhibitory phosphorylated tyrosine motifs and either CD4 or CD8, which are believed to stabilise the signalling complex. For optimal T-cell responses, co-stimulation is preferred for amplification and regulation of the initial signal. This is provided by molecules such as CD28, CD40, CD80/CD86 and OX40L. Preferably, stimulation of T-cells is carried out in vitro by mimicking a TCR signal via cross-linking of cell surface CD3, using a monoclonal antibody (anti-CD3). This ultimately results in cell cycle entry and, as T-cell stimulation induces transcription factor activation, gene transcription, protein synthesis and protein trafficking, methods of the invention aim to identify and trace any abnormalities in these physiological processes and any consequences (e.g. differences in response to stimulus which may manifest in differences in mRNA, protein, lipid or other metabolite levels or ratios associated with such abnormalities).

Preferably, the stimulus is anti-CD3 antibody. Stimulation of T-cells may also be carried out using other agents, for example ionomycin and PMA, alone or in combination with CD3.

The term "response" as used herein may thus refer to a response elicited in response to the stimulation/activation of a resting T-cell. Such responses include proliferation, transcription factor activation or deactivation and modulation of one or more of the following: gene expression, protein synthesis, signal transduction, cytokine synthesis, protein trafficking and protein turnover, metabolite or lipid profile. Preferably, the response comprises proliferation, modulation of gene expression, protein synthesis and/or protein turnover.

Identification of differences between responses in T-cell samples from a subject having or being predisposed to a psychotic disorder, and stimulatory response in a normal subject, not affected by or predisposed to a psychotic disorder, can therefore be used to diagnose or monitor psychotic disease. Methods of the invention may comprise comparing a response in a test T-cell sample from a subject with a response to stimulation in a control. Suitable controls include normal controls derived from individuals not unaffected by or predisposed to psychotic disorder and disorder controls derived from individuals with a psychotic disorder preferably a schizophrenic disorder.

Methods of the invention may comprise detecting a difference in a response between the test sample and a control sample. Thus, methods of the invention may involve comparing a response in a test T- cell sample with a response in a normal control T-cell sample, wherein a difference in response is indicative of the presence of or predisposition to a psychotic disorder such as a schizophrenic disorder. Differences in response may be detected as a presence, absence, increase or decrease in a particular response to stimulus. Alternatively or additionally, methods of the invention may comprise a response in a test T-cell sample with a response in a psychotic disorder control T-cell sample, to enable the test T-cell response to be matched to the response characteristic of a particular psychotic disorder; such comparisons are useful for differential diagnosis of psychotic disorders that present with similar or overlapping clinical symptoms.

Following stimulation, T-cells from schizophrenia patients have been found to have significantly lower proliferation compared to healthy controls, as illustrated in Example 2 of WO2007/063333. Thus, in those embodiments where the response is proliferation, a lower proliferation in a T-cell sample from a subject compared to proliferation in a normal control T-cell sample is indicative of a psychotic disorder, in particular schizophrenia, being present. Proliferation may be assessed by ³[H]- thymidine incorporation into progeny cell DNA, as illustrated in Example 1 of WO2007/063333.

Differences in responses of T-cells from individuals having or predisposed to psychotic disorders and those from normal individuals may also be detected by assessing modulation in gene expression in response to exposure to stimulus, preferably in response to exposure to a stimulus for T-cell proliferation. Differences in responses may also be assessed by considering the downstream effects of differential gene expression in subjects having or being predisposed to a psychotic disorder, e.g. differences in metabolic profile, lipid profile, or differences in levels or ratio of biomarkers, compared to those in normal individuals not suffering from or predisposed to a psychotic disorder.

The terms "modulated" and "modulation" are used herein to mean an upregulation or downregulation of expression of a gene or differences in the proteome, for example, an increase or decrease in protein level. Modulation of gene expression can be measured by detecting a variation in mRNA or protein levels. The increase or decrease in protein level may be assessed by simply determining the presence or absence of a protein or by using a quantitative method.

Methods of determining the expression level of a gene are well known in the art. According to the methods of the invention, modulation of expression can be identified by assessing the amount or concentration of mRNA, a nucleic acid derived from mRNA or a protein translated from the mRNA. Gene expression may be measured by assessing mRNA levels using a method including reverse transcription and polymerase chain reactions ("RT-PCR"), such as quantitative PCR (in particular, real-time quantitative PCR), and Northern blotting. In one suitable method for determining the level of mRNA expressed, a total RNA sample is obtained from the cell, cDNA is synthesized from mRNA of the gene or genes of interest, and the cDNA is used for real-time quantitative PCR analysis to determine the level of the mRNA of interest in the sample. Systems and kits for implementing such methods are commercially available.

Arrays may be used to assess expression of a plurality of genes or proteins, for example using weak cation exchange (CM10) chips for SELDI analysis of proteins, or Codelink Bioarrays for gene expression. An example of a method used to assess gene expression is shown in Example 3 of WO2007/063333.

Examples of suitable methods for determining the level of protein expression or identifying protein biomarkers include immunological methods, involving an antibody, or an antibody fragment capable of specific binding to the protein of interest. Suitable immunological methods include sandwich immunoassays, such as sandwich ELISA in which detection of the peptide is performed using two antibodies which recognize different epitopes; radioimmunoassays (RIA), direct or competitive enzyme-linked immunosorbent assays (ELISA), enzyme-immuno assays (EIA), Western blotting, immunoprecipitation and any particle-based immunoassay (e.g. using gold, silver, latex or magnetic particles or Q-dots). Immunological methods may be performed, for example, in microtitre plate or strip format.

Other techniques that may be used in the methods of the invention, for example for the detection, identification and/or quantification of a biomarker, e.g. for quantifying the level of a nucleic acid, protein, lipid or metabolite present, include spectral analysis, such as NMR spectroscopy and high resolution NMR spectroscopy (¹H NMR), mass spectrometry, such as Surface Enhanced Laser/Desorption Ionization (SELDI) (-TOF) and/or MALDI (-TOF), 1-D gel-based analysis, 2-D gel- based analysis, LC-MS-based technique or iTRAQ™. An example used to analyse proteins is shown in Example 4 of WO2007/063333. iTRAQ™ technology involves the chemical tagging of N-terminus peptides resulting from protein digestion with trypsin. Up to four labelled samples are combined, fractionated by nano-LC and analysed by tandem mass spectrometry. Protein identification is then achieved by database searching of fragmentation data. Relative quantification of peptides is achieved by fragmentation of the chemical tag, which results in a low molecular weight reporter ion. As samples are labelled after tryptic digestion, analysis of high molecular weight proteins such as trans-membrane receptors is possible and quantification of fragmented tag provides greater confidence in protein identity and quantification.

According to the invention, a suitable cohort of patients and controls may be selected including first onset and/or minimally treated individuals and these will be compared with chronically ill patients having a more established clinical history. This allows comparison of both disease progression and the effects of drug treatment. Membrane-bound and soluble proteins may be prepared from stimulated T-cells. Thus, proteomic profiling of T-cells from psychosis patients and controls may be performed, providing information regarding differing expression of large and small molecular weight proteins, e.g. phosphoproteins, following stimulation. Methods of the invention may comprise comparing samples by assessing variation in one or more biomarkers in response to stimulation of the sample. The term "biomarker" means a distinctive biological or biologically-derived indicator of a process, event, or condition. Biomarkers can be used in methods of diagnosis (e.g. clinical screening), prognosis assessment; in monitoring the results of therapy, identifying patients most likely to respond to a particular therapeutic treatment, drug screening and development. Preferably, the biomarker is a gene, mRNA, a protein or peptide, lipid, or metabolite. The terms protein and peptide are used interchangeably herein. The biomarker may be quantified. Biomarkers and uses thereof are valuable for identification of new drug treatments and for discovery of new targets for drug treatment. Quantifying the amount of the biomarker present in a sample may include determining the concentration of the peptide biomarker present in the sample. Detecting and/or quantifying may be performed directly on the sample, or indirectly on an extract therefrom, or on a dilution thereof. Detecting and/or quantifying can be performed by any method suitable to identify the presence and/or amount of a specific protein in a biological sample.

In one embodiment, the control sample comprises a normal control sample. In another embodiment, the control sample comprises a psychotic disorder control sample. In another embodiment, the method may also comprise classifying proliferative responses of a sample as having a normal profile, psychotic disorder profile, or psychotic disorder predisposition profile.

In methods of the invention, in particular those for diagnosing and monitoring, T-cell samples may be taken on two or more occasions from a test subject. Stimulatory responses from samples taken on two or more occasions from a test subject can be compared to identify differences between the stimulatory responses in samples taken on different occasions. Methods may include analysis of stimulatory responses from biological samples taken on two or more occasions from a test subject to quantify the level of one or more biomarkers present in the biological samples, and comparing the level of the one or more biomarkers present in samples taken on two or more occasions. Diagnostic and monitoring methods of the invention are useful in methods of assessing prognosis of a psychotic disorder, in methods of monitoring efficacy of an administered therapeutic substance in a subject having, suspected of having, or of _o

being predisposed to, a psychotic disorder and in methods of identifying an antipsychotic or pro-psychotic substance. Such methods may comprise comparing the level of the one or more biomarkers in a test biological sample taken from a test subject with the level present in one or more samples taken from the test subject prior to administration of the substance, and/or one or more samples taken from the test subject at an earlier stage during treatment with the substance. Additionally, these methods may comprise detecting a change in the level of the one or more biomarkers in biological samples taken from a test subject on two or more occasions.

A method of diagnosis or monitoring according to the invention may comprise quantifying the one or more biomarkers in a test biological sample taken from a test subject and comparing the level of the one or more biomarkers present in said test sample with one or more controls. The control can be selected from a normal control and/or a psychotic disorder control. The control used in a method of the invention can be selected from: the level of biomarker found in a normal control sample from a normal subject, a normal biomarker level; a normal biomarker range, the level in a sample from a subject with a schizophrenic disorder, bipolar disorder, related psychotic disorder, or a diagnosed predisposition thereto; a schizophrenic disorder marker level, a bipolar disorder marker level, a related psychotic disorder marker level, a schizophrenic disorder marker range, a bipolar disorder marker range and a related psychotic disorder marker range.

Detecting differences in responses enables identification of biomarkers for a psychotic disorder. The response may be assessed by any suitable method or combination of methods, for example by considering gene expression, at the mRNA and/or protein level, to detect differential gene expression between disorder and control samples, by considering protein levels (e.g. in cell lysate), lipid profile and/or metabolite profile. The differences may manifest as the presence or absence of a biomarker or a difference (increase or decrease) in level of a biomarker, or in ratios of a biomarker or biomarkers.

Differences in gene expression can be detected by a modulation in mRNA or protein levels. Where the biomarker is a gene, the expression of the gene present in the disorder sample may be modulated compared to the expression of the gene in the control sample, thus different levels of mRNA transcribed from the gene will be detected. For example, the expression may be increased or decreased, or different splice variants or ratios of splice variants of the mRNA may be detected. In another embodiment, the biomarker is a protein and the level of the protein present in the sample differs from the level of the protein present in the control sample. For example, the level may be modulated so that it is increased or decreased, or a difference in protein cleavage products may be found; this may be assessed by a quantitative method or determined by the presence or absence of the protein.

In one embodiment, the level or ratio of one or more biomarkers is detected. This may be carried out using a sensor, e.g. a biosensor comprising one or more enzymes, binding, receptor or transporter proteins, antibody, synthetic receptors or other selective binding molecules for direct or indirect detection of the biomarkers. For detection, the sensor may be coupled to an electrical, optical, acoustic, magnetic or thermal transducer.

The term "antibody" as used in this embodiment includes, but is not limited to, polyclonal, monoclonal, bispecific, humanised or chimeric antibodies, single chain antibodies, Fab fragments and F (ab')₂ fragments, fragments produced by a Fab expression library, anti-idiotypic (anti-Id) antibodies, and epitope-binding fragments of any of the above. The term "antibody" as used herein also refers to immunoglobulin molecules and immunologically-active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that specifically binds an antigen. The immunoglobulin molecules of the invention can be of any class (e. g., IgG, IgE, IgM, IgD and IgA) or subclass of immunoglobulin molecule.

Biomarkers identified using a method of the invention can be used as biomarkers for a psychotic disorder or predisposition thereto. They are thus useful in methods for monitoring or diagnosing psychotic disease.

The present invention may be used identify a potential therapeutic agent for the prevention, treatment or amelioration of a psychotic disorder. In one embodiment, the invention comprises comparing a response to stimulation with a response in a control sample. In particular, responses in test and normal control T- cell samples exposed to a candidate therapeutic agent may be compared, identifying the candidate as a potential therapeutic agent if one or more responses in the test T- cell sample are modulated such that a normal response is restored.

According to this aspect, a candidate therapeutic agent is identified if the candidate therapeutic agent is capable of modulating a response in T-cells from a subject having a psychotic disorder, in particular such that one or more responses are restored to the response characteristic of T-cells from normal individuals. Preferably, the response is proliferation or modulation of gene expression, i.e. changes in mRNA or protein levels. The response can be assessed using the methods described herein, in particular by assessing biomarkers of response identified as described herein. Changes in proliferation can be assessed by comparing the proliferation of T-cells in the presence and absence of the candidate therapeutic agent. Modulation of expression of one or more genes can be assessed by comparing the expression level of the gene or genes (at the mRNA or protein level) in the presence and absence of the candidate therapeutic agent. Modulation of protein levels can be assessed by comparing the level of the protein or proteins in the presence and absence of the candidate therapeutic agent. Other suitable biomarkers of response include lipids and metabolites found at different levels in disorder and normal control samples.

In another aspect, the invention relates to a diagnostic kit or monitoring kit suitable for performing a method described herein. Kits according to the invention may comprise one or more components selected from: instructions for use of the kit, one or more normal and/or psychotic disorder controls, a sensor or biosensor suitable and/or adapted for detecting a biomarker according to the invention and a ligand, e.g. nucleic acid, antibody, aptamer, or the like, capable of specifically binding a biomarker according to the invention or specifically binding a substance derived from the biomarker or from the action of the biomarker. The ligand may be provided immobilised on a solid support such as bead or surface, for example in the form of an array adapted for use in a method of the invention.

The following Examples illustrate the invention. They should be read in conjunction with the drawings, in which each of Figures 1 to 5 is a graph of label incorporation in a particular test. Example 1

This Example was conducted in order to investigate the origins of lower T-cell responses in patients, and more specifically to determine whether they derive from cell extrinsic factors such as oxidative stress or hormones the cells have been exposed to whilst in the patients body. This has been investigated by incubating T- cells from healthy donors in the presence of drug-naϊve patient and matched control serum. T-cells from healthy volunteers were cultured in 96-well plates coated with 0 or 1 μg/ml anti-CD3 (clone OKT3) in RPMI-1640 medium supplemented with 1% GPS in the presence of 10% patient and matched control serum. T-cell proliferation was measured by 3[H]-thymidine incorporation. As the number of serum samples per experiment was limited by the amount of T-cells obtained from a single donor, the proliferation measurements were divided into two independent studies. Each study comprised serum samples from a cohort of six patient and six matching healthy control subjects which were incubated with 18 T-cell samples from healthy donors in the first and 11 T-cell samples in the second study. Experiments were performed under identical conditions by independent researchers, making the second study a validation of the first. _u

Statistical analysis of both datasets revealed that serum from schizophrenia smokers induced significantly higher proliferative T-cell response (fold change: 1.3) when compared with serum from healthy control smokers (p = 0.0012) (Fig. 1). This response was also significantly increased (fold change: 1.3) in comparison to T-cells treated with serum from schizophrenia non-smokers (p = 0.0004). Interestingly, no difference in proliferation was found between healthy control smokers and non- smokers, suggesting that altered proliferative response was not induced by components of cigarette smoking alone. A drug effect for the higher proliferative T-cell responses can be excluded, as serum samples used in both studies derived from drug-naϊve, first-onset schizophrenia patients. In addition, cotinine concentrations were measured in the same serum samples used for assessing proliferative response. No differences were observed between the two groups. Cotinine levels correlated strongly with the amounts of cigarettes consumed per day but did not correlate with proliferation of T-cells, further ruling out smoking as the sole factor contributing to the difference in proliferation, Example 2

This Example was conducted under the assumption that early T-cell activation events are reflected in the level of expression of T-cell surface markers. The effect of patient serum from smokers on these was investigated before and after stimulation with OKT3-Ab. T-cells from 12 healthy donors were treated with two representative serum samples (two control and two patient smokers) from the proliferation study and stained for cell surface markers in a four-colour staining combination.

Patient serum induced enhanced down-regulation of TCR complex molecules: T-cells respond to antigen recognition by proliferation which is tightly regulated by degradation of the T cell receptor (TCR) complexes TCRoc/β and CD3 shortly after T-cell activation. The expression of down-regulated TCR complexes was measured after T-cell stimulation. The median Fl of the TCRce/β receptor was down- regulated to a greater extent on stimulated CD4+ (p = 0.0049) and CD8+ (p = 0.0122) cells by patient compared to healthy control serum. In addition, the CD3 antigen was significantly more strongly down-regulated by patient serum on CD4+ cells (p = 0.0068).

Patient serum induced enhanced up-regulation of co-stimulatory molecules; T-cell activation can also be evaluated by the expression of co-stimulatory molecules. The expression of CD26, a dipeptidyl peptidase IV (DPP IV) cell surface protease, CD27, a member of the tumor necrosis factor (TNF) receptor family and CD28 were measured. All receptors were significantly enhanced up-regulated by patient serum compared to control serum in stimulated CD4+ and CD8+ cells .

Patient serum promoted active cell types: T-cell activation through antigen stimulation evokes de novo expression of distinct activation markers. The expression of early and late activation markers CD25 and CD69 on CD4+ and CD8+ cells was analysed. Cells expressing CD69+ and CD25+ receptors represent a phenotype descriptive for an active cell state whereas CD69- and CD25- expressing cells represent a quiescent phenotype. In detail, frequency as well as median Fl of CD4+CD69+ and CD8+CD69+ phenotypes (Fig. 2) were significantly augmented (fold change 1.5) in stimulated T-cells (Fl: p < 0.001; p < 0.05) (%: p < 0.01 p < 0.05) exposed to patient serum. In line with these findings was the expression pattern of the CD69- population with a significantly decreased frequency on CD4+ (p < 0.001) and CD8+ (p < 0.05) cells exposed to patient serum. The expression of the IL-2 receptor chain CD25, a cell surface marker promoting T-cell proliferation, was similar to the expression of CD69+, showing an enhanced up-regulation of CD25+ and down-regulation of CD25- on CD4+ and CD8+ cells treated with patient serum.

Table 1 Chan es in ex ression of T cell surface markers after T cell activation*

^*FI = median fluorescence intensity; dark grey boxes = these cells were analysed as single populations (% = 100); Significant changes between the patient and control group are presented by p-values with *p < 0.05, **p < 0.01 and ***p < 0.001 referring to a stronger up-or down regulation by patient serum.

Example 3 The aim of this Example was to investigate differences in cytokine production by healthy T-cells treated with serum from schizophrenia smokers compared to serum from healthy smokers. Cytokine production of the antiinflammatory cytokine IL-10 (Th-2 response), the pro-inflammatory cytokine IFN-γ (Th-1 response) and the autocrine cytokine IL-2 were measured in T-cell supematants.

Cytokines were measured in unstimulated (0 h) and stimulated T-cells after, 24 and 48 h, using ELISA. There were no differences in T cell supernatant concentrations of IL-10 and IFN-γ between the two groups. There was also no difference in IL-2 T cell supernatant concentration after 24 h (Fig. 3). However, IL-2 concentration was significantly decreased (p = 0.027) after 48 h in the patient-treated T-cells (Fig. 3), supporting the stronger proliferative response of these cells. IL-2 is used by the cells in an autocrine fashion at a very early stage of T-cell activation. This result shows that patient-treated T-cells do not necessarily produce more IL-2 during the first 24 h but use it more efficiently to drive their own proliferation, compared to control-serum treated T-cells. This result furthermore coincides with the higher expression of CD25, the IL-2 receptor, as found in Example 2.

Claims

1. A method of diagnosing, predicting or monitoring a psychotic disorder in a subject, which comprises contacting a test sample from the subject with healthy T-cells, and assessing the response of the T-cells.

2. A method according to claim 1, wherein the response is lymphocyte proliferation.

3. A method according to claim 1 or claim 2, wherein the response is increased proliferation.

4. A method according to any preceding claim, wherein the response is regulation of an activation marker.

5. A method according to claim 4, wherein the activation marker is selected from CD25, CD26, CD27, CD28, CD69 and CCR7, and combinations thereof.

6. A method according to any preceding claim, wherein the response is expression of a T-cell receptor module (TCR).

7. A method according to claim 6, wherein the TCR is TCRα/β or CD3.

8. A method according to any preceding claim, wherein the T-cells are stimulated.

9. A method according to any preceding claim, wherein the sample is of serum.

10. A method according to any preceding claim, wherein the disorder is schizophrenia.