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Title:  Skin test for schizophrenia
United States Patent: 
7,070,760
Issued: 
July 4, 2006

Inventors:
 Shinitzky; Meir (Kfar Shmaryahu, IL); Deckmann; Michael (Guebwiller, FR)
Assignee: 
Yeda Research and Development Co., Ltd. (Rehovot, IL)
Appl. No.: 
555964
Filed: 
December 7, 1998
PCT Filed: 
December 07, 1998
PCT NO: 
PCT/IL98/00592
371 Date: 
September 08, 2000
PCT PUB.NO.: 
WO99/30163
PCT PUB. Date: 
June 17, 1999


 

Outsourcing Guide


Abstract

A diagnostic method for assaying schizophrenia in a subject is provided wherein a preparation comprising platelet derived proteins or fractions thereof having a pI above about 6.5 is injected into a subject and the occurrence of delayed type hypersensitivity (DTH) reaction at the site of the injection is determined. A positive DTH reaction indicates that the tested subject has a high likelihood of being schizophrenic. The protein preparation used in the diagnostic method is also provided as well as a method for its preparation and a kit for use in the diagnosis of schizophrenia using the above method.

BACKGROUND OF THE INVENTION

Schizophrenia is a syndrome which encompasses a variety of symptoms including paranoia, auditory hallucination, delusions, catatonia, bizarre behavior and emotional withdrawal. Schizophrenia affects about 1% of the total population. Its economical and social burden on society is enormous since onset occurs in youth thus requiring patients to be under medical and psychiatric supervision for most of their lives. Schizophrenia is therefore one of the most costly diseases in the industrialized world.

Since the biochemical basis of schizophrenia has not yet been elucidated, diagnosis today is still based solely upon psychiatric evaluation. Furthermore, no therapy is currently available for schizophrenia although the symptoms may be ameliorated by neuroleptic drugs.

Many reports have implicated the immune system in the etiology and course of several mental disorders. Serum antibodies which cross-react with brain antigens have been found in the blood of schizophrenic patients.sup.(1 6), thus indicating that schizophrenia is also an autoimmune disease.sup.(7 9). Furthermore, platelets have been used as a model for neuronal tissue.sup.(10,11) and elevated levels of autoantibodies to platelets have been detected in schizophrenic and demented patients, but not in patients suffering from manic-depressive disorder, depression, personality disorders or schizoaffective disorders.sup.(12 14). An assay for the diagnosis of multi-infarct dementia and dementia of the Alzheimer type was described based on detection of a high level of a platelet associated antibody.sup.(15).

A cellular response against autologous platelets was also demonstrated in schizophrenia patients who showed a delayed type hypersensitivity (DTH) reaction when injected with platelets collected from their own blood.sup.(16).

It is therefore the object of the present invention to provide a test for the diagnosis of schizophrenia in a subject.

SUMMARY OF THE INVENTION

A novel finding in accordance with the invention is that schizophrenic patients exhibit a reaction which displays characteristics of a typical delayed-type hypersensitivity reaction when injected with a specific, novel fraction of platelet proteins. This novel fraction is referred to herein as "Pool 2 proteins". The Pool 2 proteins, which constitute an aspect of the invention, are characterized by having an isolectric point (pI) which is above about 6.5 and preferably within the range of about 6.5 to about 9.5. When injected with Pool 2 proteins, schizophrenic patients show such a delayed-type hypersensitivity (DTH) reaction.

It is to be noted that although the reaction of the patients to the Pool 2 proteins is referred to above and below as a DTH reaction, there may be cases in which the time profile of the reaction of the patient to the Pool 2 proteins will be different than the time profile of a typical DTH reaction.

The present invention thus provides a protein preparation (hereinafter "Pool 2 proteins") comprising platelet derived proteins or fractiions thereof having an isoelectric point (pI) above about 6.5 and preferably within the range of above 6.5 to about 9.5, said preparation capable of eliciting a DTH reaction in a schizophrenic individual upon injection thereof to the individual.

The present invention further provides a diagnostic method for assaying schizophrenia in a subject comprising: (a) obtaining a preparation comprising, as an active component, platelet derived proteins or fractions thereof having an isoleectric point (pI) above about 6.5 and preferably within the range of about 6.5 to about 9.5 ("pool 2 proteins"); (b) injecting said protein preparation into a subject; and (c) examining the subject for the occurrence of a delayed type hypersensitivity reaction at the site of the injection, a positive result being a reaction above that which is observed in non-schizophrenic sujects, indicating that the subject has a high likelihood of being schizophrenic.

In accordance with the invention it was also surprisingly found that the Pool 2 proteins may be either prepared from autologous platelets of the individual to be tested or, alternatively, from a pool of hetrologous platelets which were obtained from a number of individuals other than the tested subject. It was also surprisingly found that, in most cases, the DTH reaction in a schizophrenic patient is substantially higher when the individual is injected with such Pool 2 proteins obtained from a pool of heterologous platelets as compared to a lower DTH reaction in the same tested individual injected with Pool 2 proteins prepared from his own autologous platelets. This finding provides the advantage of preparing a pool 2 protein preparation which may then either be used immediately or alternatively, be stored at appropriate conditions (e.g. refrigeration) and used for various periods of time to diagnose schizophrenia in a large number of individuals. This obviates the need to repeatedly obtain a blood sample comprising platelets from the tested individual immediately prior to carrying out the diagnostic assay of the invention.

Thus, by a preferred embodiment, the present invention further provides a method for the preparation of a reagent for use in diagnosis of schizophrenia, comprising: (a) obtaining blood samples from a number of individuals preparing a pool from said samples and collecting platelets therefrom; (b) preparing a protein fraction from said platelet preparation comprising proteins or fractions thereof having a pI of above about 6.5, preferably within the range of about 6.5 to about 9.5.

The Pool 2 proteins prepared from heterologous individuals may either be prepared from a number of individuals suffering from schizophrenia or, alternatively, also from a mixture of blood samples obtained from schizophrenic patients as well as healthy individuals.

The present invention yet further provides a diagnostic method for assaying schizophrenia in a subject comprising: (a) obtaining a blood sample from a number of schizophrenic and/or non schizophrenic individuals other than the tested subject and collecting platelets therefrom; (b) preparing a protein fraction from said platelet separation comprising proteins or fractions thereof having a pI of above about 6.5, preferably within the range of above 6.5 to about 9.5; (c) injecting said protein preparation into a subject; and (d) examining the subject for the occurrence of a delayed type hypersensitivity reaction at the site of the injection, a positive result being a reaction above that which is observed in non-schizophrenic subjects, indicating that the subject has a high likelihood of ein schizophenic.

By a preferred embodiment, a method for diagnosis of schizophrenia in an individual is provided as above wherein the protein fraction collected in stage (b) is then stored as appropriate conditions for repetitive use as described in stages (c) and (d) above at later priods of time for a number of tested individuals.

Although, as explained above, there is an advantage in preparing a pool of Pool 2 proteins from a number of individuals other than the individual to be tested, in accordance with the diagnostic method of the invention, it is also possible to use Pool 2 preparation prepared from autologous platelets of the individual to be tested.

The present invention thus provides a diagnostic method for assaying schizophrenia in a subject comprising: (a) obtaining a blood sample from an individual and collecting platelets therefrom; (b) collecting proteins or fractions hereof from said platelet sample, said proteins or fractions having a pI of above about 6.5, preferbly within the range of about 6.5 to about 9.5; (c) injecting said collected protein or fractions thereof to the tested individual; and (d) examining the subject for the occurrence of delayed type hypersensitivity reaction at the site of the injection, a positive result being a reaction above that which is observed in non-schizophrenic subjects, indicating that the subject has a high likelihood of being schizophrenic.

Typically, the Pool 2 proteins will be collected by subjecting the collected platelet proteins to isoelectric focusing wherein the proteins haveing a pI of above about 6.5, preferably within the range of 6.5 to 9.5 are collected by methods known in the art.

However, in accordance with the invention it has also been found that the Pool 2 protein preparation may also be prepared by methods which do not include isoelectric focusing such as, for example, by extracting the proteins from the platelet sample using for example a detergent, such extraction resulting in Pool 2 proteins having the desired pI values and capable of eliciting a DTH reaction in a schizophrenic patient.

If desired, the Pool 2 protein preparation obtained by any one of the methods mentioned above may be subject to further fractionation steps, e.g. by thin layer chromatography, by high pressure liquid chromatography or by many other purification fractionation methods known, per se. Fractions thus obtained can each then be tested for activity, namely for its ability to cause the DTH reaction in schizophrenic patients. Such purified fractions, as well as individual proteins, polypeptides or peptides among the Pool 2 proteins which are active in eliciting he DTH reaction in schizophrenic patients, are also an aspect of the invention.

The Pool 2 protein preparation prepared in accordance with the invention and used in the diagnostic methods of the invention include proteins purified from the Pool 2 proteins, polypeptides or peptides comprising sequences of such proteins, fractions thereof, as well as proteins, polypeptides or peptides obtained by synthesis or by genetic engineering having a sequence identical to that of the proteins of the Pool 2 proteins.

In accordance with the invention, Pool 2 proteins used in the diagnostic assay of the invention are such which are capable of eliciting DTH activity in an injected individual, the DTH activity being tested by the test known in the art. In short, the Pool 2 proteins are intradermally injected into the tested individual at the forearm or thigh and the reaction at the injection site is evaluated after 24, 48 and 72 hours by measuring the reaction diameter around the induration. As mentioned above, there may be cases in which the time profile of the reaction will differ from the typical time profile of a DTH reaction.

The present invention further provides a kit for use in diagnosis of schizophrenia, comprising said Pool 2 proteins, active protein fractions obtained therefrom, or individual active proteins or peptides, derived from said Pool 2 proteins. Preferably, such proteins are provided in either injectable form or in a form suitable for preparing an injectable formulation, e.g. a lyophilysate. Typically, the kit will be provided with instructions for use or a chart or pictures for guidance of the manner of scoring the results.
 


Claim 1 of 4 Claims

1. A method for the preparation of a reagent for use in diagnosis of schizophrenia in an individual by detecting a DTH reaction in said individual following injection of said reagent to the individual, comprising a) obtaining blood samples from a number of individuals, preparing a pool from said samples and collecting platelets therefrom; b) preparing a protein fraction from said platelet preparation comprising proteins or fractions thereof, wherein the pI of said proteins or fractions thereof is about 6.5 to about 9.5; c) injecting the platelet preparation of step b) into a subject; and d) detecting the occurrence of a DTH reaction at the site of injection, wherein a positive result is a reaction above that observed in a non-schizophrenic subject under similar conditions, and it indicates that the subject has a high likelihood of being schizophrenic.

 

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If you want to learn more about this patent, please go directly to the U.S. Patent and Trademark Office Web site to access the full patent.

 

 

     
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