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* Recurrent abortion has always been a frustrating problem for both the patient and the physician . Although a well defined cause for the abortions may exist, yet, in the fast majority of cases the clinicianصs investigative checklist fails to detect the cause , the etiology remains unknown in approximately 50 % of cases . Recently , it has been suggested that the commonest etiology in this group of patients is an immunological cause. The causes of recurrent reproductive wastage are varied and complex . for this purpose the present work was designed to focus on the rule of immunologic factors in cases where other causes were not evident and to elucidate a possible immunological factor that might contribute to the etiology of recurrent spontaneous abortion* This study comprised 60 female patients presenting with unexplained recurrent spontaneous abortion . after exclusion of known general , anatomic , endocrinologic , infectious causes and twenty normal fertile females , having at least two uncomplicated full term deliveries , served as controls . All recurrent spontaneous abortion and control couples were subjected to the following .- Careful history taking and physical examination and exclution of other possible causes of recurrent spontaneous abortion.* Peipheral blood samples were taken from all patient for in vitro lymphocyte proliferation assay to calculate the stimulation index also for embryotoxic factor assay using trophoblast antigens ( National cancer institute )- From this present work , the obtained results showed that* 32 ( 56.1 %) women with recurrent abortion of unknown cause responded to trophoblast antigen stimulation with a stimulation index > 3, whereas none of the control group responded . Neither patients with recurrent abortion nor women with normal reproductive histories responded to red blood cell membrane antigen .* The mean stimulation index in the trophoblast antigen lymphocyte proliferation assay was significantly higher in women with recurrent abortion than in women with normal reproductive histories .* Lymphocyte proliferation correlated with embryotoxic factor production in 27 (84.4 %) of 32 women with a stimulation index > 3 and none of the controls produced embryotoxic factors after stimulation with trophoblast antigens whereas10 ( 40 %) of 25 women with recurrent abortion had evidence of embryotoxic factors in spite of stimulation index < 3 .* Trophoblast antigen derived from cytosol and membrane components was responsible for lymphocyte proliferation in the majority of cases .CONCLUSION* The lymphocyte proliferation assay appears to provide an effective method to distinguish women with activated cellular immunity to trophoblast , which may contribute to their abortions . This technique , in addition to the embryotoxic factor assay , may be useful in the diagnostic evaluation of women with recurrent abortion and have applicability regarding the testing of potential therapeutic modalities , such as immunosuppressive therapy . The embryotoxic factor assay appears to be a more permissive test because as many as 10 % of women may have been incorrectly diagnosed by means of the lymphocyte proliferation assay alone . Performance of both assays may provide assurance that a positive value is indeed positive , because both assays are designed to uncover the same potential cause for pregnancy loss , namely , aberrant cellular immunity to trophoblast antigen stimulation .- These data ( lymphocyte proliferation & the embryotoxic factors assay ) may provide a diagnostic tools to predict the outcome of pregnancy .RECOMMENDATIONS* We found evidence for activated cellular immunity to trophoblast antigen in women with recurrent abortion , cause-versus-effect relationships need to be further defined .* The possibility also exists that in a subgroup of women a spontaneous abortion from whatever cause may sensitize the maternal immune system to trophoblast so that future pregnancies end in failure because of trophoblast-antigen-activated maternal cellular immunity so further work is needed to analyze these possiblilities and to more fully characterize the trophoblast antigen(s) responsible for cellular immunity in women with recurrent abortion.* Experimental testing of nulligravida women , women with unexplained infertility, and those after one pregnancy loss may also be informative. Optimization of these potential diagnostic assays is also needed .* Establishment and characterization of T-cell lines from these women may enable more information to be obtained concerning the specific trophoblast antigen(s) causing cellular immunity and the specific cytokines or other soluble cell factors involved in mediating abortion so animal models are also needed for this potential new mechanism of recurrent abortion.REFERENCES- Abbas A k, Lichtman A H and Pober J S ( 1991 ):The major histocompatibility complex.Cellular and Molecular Immunology.WB Saunders ; 98. 620 : 677 , 1991.
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