Characterization of clonogenic stromal cells isolated from human endometrium.

Human endometrium is an object of extensive restructuring and remodeling during the female reproductive life and it is quite tempting to assume that these periodic changes happen with the participation of cells that should have the basic characteristics of multipotent cells. The aim of this study was to search for the presence of cells with plastic adherence, clonogenicity, and differentiation in human endometrium. To this end, human endometrial stromal cells were cultured in vitro for more than 15 passages. Flow cytometry analysis of the cultured cells showed that they were positive for CD29, CD73 and CD90, which are considered to be the markers of cells with mesenchymal origin. The cells were negative for the hematopoietic cell markers (CD45, CD34, CD14, CD3, CD19, CD16/56, and HLA-DR). Further, it was shown that the cultured cells had 15% clonogenic efficiency and could be induced to differentiate into adipogenic cells containing typical lipid-rich vacuoles. These results demonstrate that the human endometrium contains a low number of cells with the characteristics of endometrial stromal stem/progenitor cells, which seem to belong to the family of the mesenchymal stem cells. It can be speculated that these cells are engaged into the monthly restructuring and remodeling of human endometrium.

Dynamics of membrane translocation of phosphatidylserine during apoptosis detected by a monoclonal antibody.

Translocation of phosphatidylserine (PS) to the outer leaflet of the cellular membrane seems to be a key step in apoptosis and cell activation. In this paper, the production and characterization of a monoclonal antibody designated as Mab 1H6 is described which does not show cross reactivity with others anionic phospholipids. It is demonstrated that Mab1H6 can recognize externalized PS at early stages after the induction of apoptosis shown by both flow cytometry and immunofluorescence. Our results show that translocation of PS can be detected as early as 5 min by immunofluorescence and 10 min by flow cytometry after the treatment of cells and a specific dynamics is observed concerning the location and distribution of the staining. These data prove that antibody Mab 1H6 can be used as a specific probe for detection of PS translocation.

Immunocytochemical localization of atrial natriuretic factor (ANF) in rat female reproductive tract: evidence for a potential hormonal regulation.

In the present studies atrial natriuretic factor (ANF) was characterized immunocytochemically in the reproductive tract of immature female rats, and changes of ANF levels in response to different hormonal conditions were demonstrated. Administration of pregnant mare serum gonadotropin (PMSG) to immature animals has shown to be a useful method to synchronize growth, differentiation and atresia of ovarian follicles. ANF immunoreactivity was investigated in rat uterus and oviduct during follicular growth and estrogenic dominance (48 h after PMSG treatment) and during follicular atresia and progesterone dominance (96 h after PMSG treatment). Our immunocytochemical results showed that in rat uterus ANF was localized in endometrial mucosal and glandular epithelium and smooth muscle cells of the myometrium. In the oviduct ANF immunoreactivity was observed in mucosal cells and muscle layers. Immunocytochemical staining patterns and Western blot analysis revealed that ANF levels in rat uterus and oviduct are modulated by the hormonal status. ANF immunoreactivity was elevated during estrogenic dominance (48 h after PMSG) in uterus and oviduct. However, during progesterone dominance (96 h after PMSG) elevation of ANF immunoreactivity was observed in the uterus only. These results raise the possibility that ANF expression in rat oviduct is positively controlled by estrogen and negatively by progesterone. ANF staining in uterus during progesterone phase provides evidence that both estrogen and progesterone regulate ANF levels in uterus. The observed staining patterns indicate that ANF may have intracellular functions as well as a role in priming the extracellular environment. Accordingly, the possibility that ANF might be an important regulatory molecule for autocrine/paracrine communication within the female reproductive tract should be considered.

Lupus-specific kidney deposits of HSP90 are associated with altered IgG idiotypic interactions of anti-HSP90 autoantibodies.

Previous studies have shown that autoantibodies to heat shock protein 90 (HSP90) are elevated in a significant proportion of patients with systemic lupus erythematosus (SLE) who are more likely to have renal disease and a low C3 level. Using samples from 24 patients, we searched for glomerular deposits of HSP90 in renal biopsy specimens from seven patients with lupus nephritis and 17 cases of glomerulonephritis from patients without SLE. Positive glomerular immunofluorescent staining for HSP90 was observed in six of seven cases of SLE and positive tubular staining in two of seven SLE patients. The staining for HSP90 was granular in nature and was located in subepithelial, subendothelial and mesangial areas. None of the non-SLE renal biopsies revealed positive staining for HSP90 deposition. Further we showed the presence of anti-HSP90 IgG autoantibodies in IgG from sera of patients with SLE as well as in normal human IgG (IVIg). In normal IgG this autoreactivity could be adsorbed almost completely on F(ab')2 fragments from the same IgG preparation, coupled to Sepharose and could be inhibited by the effluent obtained after subjecting normal IgG to HSP90 affinity column. These findings indicate that anti-HSP90 natural autoantibodies are blocked by idiotypic interactions within the IgG repertoire. Unlike natural autoantibodies, anti-HSP90 IgG from SLE patients' sera were only moderately adsorbed on F(ab')2 fragments of normal IgG. These results demonstrate that immunopathogenesis of lupus nephritis is associated with HSP90 (as an autoantigen) and that the pathology is associated with altered idiotypic regulation of the anti-HSP90 IgG autoantibodies.

Antimeasles immunoglobulin G in sera of patients with otosclerosis is lower than that in healthy people.

BACKGROUND: There is some evidence for an inflammatory process as a driving force in otosclerosis. Two popular hypotheses for the induction of this chronic inflammation have been proposed: an autoimmune phenomenon induced by an otic capsule specific antigen and measles virus infection. METHODS: Antibodies against measles virus hemagglutinin, polymerase, nucleocapsid, and matrix proteins were evaluated in sera from otosclerotic patients and in sera from healthy age-and sex-matched controls by use of the Western blot analyses. RESULTS: Significant differences were not detected between healthy men and women or between otosclerotic men and women. There were significantly stronger reactions against all viral proteins in the group of healthy women as compared with otosclerotic women despite a high standard deviation. The group of healthy male blood donors demonstrated significantly stronger reactions against polymerase and nucleocapsid proteins. Healthy blood donors again demonstrated stronger reaction compared with respective otosclerotic patients in a separate reaction for viral matrix protein. CONCLUSION: Our observation is consistent with viral participation in otosclerotic pathogenesis, but it is difficult to say if the diminished antimeasles humoral response is a consequence or the cause for a local measles infection. In light of the present data, we can discuss autoantibodies in otosclerosis as a sign of autoimmunity triggered by measles virus.

Immunohistochemical detection of atrial natriuretic factor (ANF) in different ovarian cell types.

OBJECTIVE: Atrial natriuretic factor (ANF) and its receptors were identified in various tissues and organs including the female reproductive system. The present studies were undertaken to investigate ANF localization in immature rat ovaries, and the changes of ANF expression in response to different ovarian hormonal conditions. METHODS: ANF was characterized immunocytochemically during different ovarian status using an animal model with synchronized ovarian follicular growth and atresia induced by pregnant mare serum gonadotropin (PMSG). This treatment in prepubescent rats produces a series of ovarian changes mimicking follicular growth and differentiation (48 h after PMSG treatment) and atresia (96 h after PMSG treatment) and permits the synchronization of events for investigation purposes. RESULTS: Our findings showed that in immature rat ovaries ANF was localized primarily in granulosa cells of all developing follicles (healthy and atretic). Immunocytochemical analysis revealed that during follicular growth and differentiation (48 h after PMSG) ANF was present in all steroid producing cells - interstitial, thecal and granulosa cells. ANF immunoreactivity was also detected in the cytoplasm and nuclear compartment of the growing oocytes. In all atretic follicles ANF staining was detected at 96 h after PMSG injection, but the intensity of the reaction varied with the degree of atresia, the mostly pronounced reaction being observed in the late stage of atresia. CONCLUSIONS: These results indicate that ANF represents a unique peptide, which is expressed in different ovarian cell types and responds to different developmental programming.

Spatial and temporal distribution of atrial natriuretic factor in the rat testis.

The atrial natriuretic factor (ANF) is a cardiac hormone whose gene and receptor are widely expressed in extracardiac tissues and organs. ANF induces its biological effects by binding to its specific guanylyl-cyclase-A receptor, which synthesizes the intracellular second messenger cGMP. Increasing evidences indicate that the testis shows the highest reactivity of stimulation of guanylate cyclase by ANF. The well-established functionally active ANF receptors in seminiferous tubules raise the question of the origin and function of ANF in the testis. Therefore, the current study was carried out to investigate the spatial and temporal distribution of ANF in the rat testis by use of immunocytochemistry. Our immunocytochemical results showed that at different pre- and postnatal ages of testicular development ANF was constantly expressed in Leydig cell cytoplasm. However, the intensity of immunoreaction varied between the different Leydig cell populations (fetal, progenitor and immature) and apparently depends on the acquisition of testosterone producing ability. In seminiferous tubules ANF staining was established in the cytoplasm of the developing spermatocytes, in degenerating germ cells (23-day of age) in the cytoplasm of Sertoli cells, cap phase of acrosomal development and in the spermatids (55-day of age). The observed staining patterns suggest a broader spectrum of ANF activities and a possible participation in the whole process of regulation of germ cell development. Our data provide additional support for the hypothesis that ANF plays a major role in autocrine/paracrine regulation of the rat male gonad.

Reduced concentrations of soluble adhesion molecules after antioxidant supplementation in postmenopausal women with high cardiovascular risk profiles--a randomized double-blind study.

BACKGROUND: One of the suggested mechanisms of increased cardiovascular risk in postmenopause is a loss of the antioxidant effects of estrogens. It has been shown that classical cardiovascular risk factors increase oxidative stress on the arterial wall, and that endothelial cells react to this insult by increased expression of cellular adhesion molecules (CAM), which in turn are markers of arterial wall inflammation. METHODS: A randomized, placebo-controlled, double-blind study was performed in 60 postmenopausal women with high cardiovascular risk profiles, but free from clinical atherosclerotic disease. Patients were randomized to either antioxidant supplementation (using a combination of natural antioxidants; n = 30) or placebo (n = 30), and followed for 12 weeks. The concentrations of the adhesion molecules sVCAM-1 and sICAM-1 were measured by ELISA at baseline and at the end of the study, as well as total cholesterol, LDL, HDL, triglycerides and blood pressure. RESULTS: 27 women in the antioxidant supplementation group and 29 on placebo completed the study. At baseline, there were no significant differences in measured parameters between the groups: sICAM-1 concentrations were 341.8 +/- 116.9 vs. 349.9 +/- 104.6 ng/ml (active treatment vs. placebo; p = n.s.) and sVCAM-1 concentrations were 780.5 +/- 325.8 vs. 761.0 +/- 333.7 ng/ml (p = n.s.). In contrast, at the end of the study, sICAM-1 concentrations were 301.6 +/- 56.0 vs. 356.0 +/- 134.8 ng/ml (active treatment vs. placebo; p = 0.053) and sVCAM-1 concentrations were 656.0 +/- 326.5 vs. 818.5 +/- 381.0 ng/ml (p = 0.04). There were no significant differences between or changes within the groups in measured cholesterol and blood pressure. CONCLUSION: Antioxidant supplementation reduces serum concentrations of endothelium-derived adhesion molecules sICAM-1 and sVCAM-1 in postmenopausal women with high cardiovascular risk profiles.

Localisation of atrial natriuretic factor (ANF) in rat testis after Leydig cell destruction: evidence for a potential role in regulating gonadal function.

OBJECTIVE: Since the atrial natriuretic factor (ANF) is synthesized in various peripheral tissues, where it acts in an autocrine or paracrine fashion, the aim was to gain new insight into ANF expression and function in rat testis after Leydig cell destruction (LCD). METHODS: Leydig cell destruction was performed by the treatment with ethane dimethane sulphonate (EDS). RESULTS: ANF was expressed after Leydig cell destruction and total elimination (24 h and 7 days after EDS treatment) and also after Leydig cell regeneration (21 and 45 days after EDS treatment). ANF staining in the interstitial compartment was observed in apoptotic Leydig cells 24 h after treatment. In seminiferous epithelium ANF labeling was detected in Sertoli and germ cell cytoplasm with a more prominent labeling in spermatids. The degenerating germ cells were totally labeled. CONCLUSIONS: The demonstration of ANF staining in seminiferous epithelium after Leydig cells elimination and androgen deprivation suggests that Leydig cells are not the sole source of ANF in rat testis and that the seminiferous epithelium may be a new site in which ANF may be synthesized. The result indicates that ANF plays a role in regulating gonadal function.

Elevated autoantibodies in sera from otosclerotic patients are related to the disease duration.

In this study an indirect ELISA with patients' sera was performed using human collagen type II, double- (dsDNA) and single-stranded DNA (ssDNA), thyroid microsomal antigen, insulin and lysozyme as antigens. Since many preoperated otosclerotic patients demonstrated the signs of myringosclerosis (n=7). they were classified separately and compared with otosclerotic patients without myringosclerosis (n=28), with healthy controls (n=42) and with patients with tympanosclerosis (n=5) of other origin. The otosclerotic patients had serum antibodies to antigens tested similar to normal controls. However, elevated antibody levels to human collagen type II, dsDNA and ssDNA were observed only in patients with a disease duration between 3 and 5 years as compared to other otosclerotic patients. The same duration association was observed in the level of the total serum alkaline phosphatase activity. These observations would suggest that the enzymatic bone resorption is the driving force in human otosclerosis. Elevated serum autoantibodies during tissue reparation in the otosclerotic stage may be a transient response to sustained excess antigen turnover in the primary lesion.

Cross-reacting idiotypes on anti-insulin autoantibodies in autoimmune diseases, identified by monoclonal antibodies.

Investigations on the specific idiotypes of autoantibodies are supposed to help with the understanding of the control mechanisms participating in the pathogenesis of autoimmune diseases. This study describes three monoclonal antibodies (Mabs) that recognize distinct idiotypic determinants on anti-insulin autoantibodies. The preabsorption by IAA-positive sera of insulin inhibits their subsequent binding to the anti-Id, thus suggesting that the Mabs recognize epitopes located at or near the binding site of insulin autoantibodies (IAA). These idiotypes are detected in sera from patients with insulin-dependent diabetes mellitus (IDDM), which are IAA-negative, also. It is possible that the expression of the idiotypes recognized might generally be associated with induction of autoantibodies, since they were found in sera from patients with rheumatoid arthritis (RA), autoimmune thyroid disease (AITD), and cataract (K). It can be assumed that the corresponding idiotypes of these Mabs, or similar structures (sequential or conformational), are expressed on autoantibodies with various antigen-binding specificities. These data suggest that some autoimmune diseases are preceded by the secretion of autoantibodies which express a common or similar pathological idiotype.

Cell specific nuclear antigens of boar spermatozoa.

Demembranated boar sperm heads were differentially extracted at conditions involving high salt-urea, proteolysis and DNase I cleavage that mimic the conditions promoting the in vivo decondensation of the fertilizing sperm nucleus in the egg ooplasm. The sperm-unique subset of proteins was studied which remained bound in the residual salt-resistant nuclear structure operationally defined as sperm nuclear matrix. By means of polyvalent antisera the immune specificity of the sperm nucleoprotein complex was estimated using ELISA and microcomplement fixation test as compared to somatic type dehistonized chromatin of boar liver. To define immunologically specific sperm DNA-associated proteins hybridomas were generated by fusing lymphocytes immunized with boar sperm protein/DNA complex. Monoclonal antibodies were selected (Mab 1A8, 1B3, 2B5, 2H5 and 3A4) which identified protein moieties in the sperm DNA-tight binding proteins complex resistant to cleavage with DNase I and sensitive upon digestion with high concentration of proteases. No appreciable reactivity was recorded of the antibodies to somatic chromatin and no significant binding to ssDNA. A polypeptide in the residual sperm nuclear structure of apparent Mr 27 kDa was recognized by Mab 3A4 as detected by Western blotting. The enhanced reactivity to the DNase I digested sperm nuclear fraction (except for Mab 2H5) suggests that DNA protected from nuclease digestion by a protein might be essential for immune reactivity and full antigenic integrity as well as the dependence of the cognate proteins on the binding to DNA for antigenicity and immune specificity. The functioning of the identified putative sperm specific proteins is anticipated in the structural rearrangement of chromatin in the zygote.

Characterization of a sperm nuclear protein.

PROBLEM: The molecular identity of sperm DNA-binding structural proteins contributing to the integrity of a sperm residual high salt/nuclease resistant nuclear structure is studied by cDNA cloning and monoclonal antibodies to the recombinant polypeptide. This structure, which is likely to be transferred unimpaired in the oocyte and is anticipated as a molecular correlate of the nuclear scaffold (nuclear matrix/envelope) in somatic cells, may be essential with respect to its DNA organization for the recovery and assembly of somatic-type chromatin in the zygote. Recently, a cDNA encoding one of these proteins has been cloned and the recombinant polypeptide expressed in E. coli as a beta-galactosidase fusion protein. The main objective of the present study is the identification of the native sperm antigen by monoclonal antibodies raised against the recombinant molecule. METHODS: We evaluated the possibility of immunizing by direct intrasplenic deposition in BALB/c mice of the recombinant fusion protein available as transblotted on nitrocellulose membrane carriers or as nitrocellulose protein-bearing particles. Isolated sperm DNA/tight binding protein complexes were used in ELISA and Western blotting for selection of monoclonal antibodies specific to self epitopes of the nuclear antigen, as well as immunofluorescence of swollen human spermatozoa subjected to in situ extraction with high salt/beta-mercaptoethanol/DNase I and proteolysis, and of a cultured fibroblast cell line L-929. RESULTS: A monoclonal antibody, Mab 2C4, was selected which recognized a 52 kDa protein in the fraction of sperm high salt/urea resistant proteins. The target polypeptide was detected on swollen spermatozoa primarily to the post-acrosomal and/or equatorial regions whereas in nonextracted sperm cells the epitope was exceedingly unavailable. The somatic cell location of the cognate epitope was confined to the nuclear envelope displaying a cap-like pattern of staining, and also in a juxtanuclear cytoplasmic randomly coiled filamentous network and in compact bodies. CONCLUSIONS: A nuclear protein salt-stably bound to the sperm residual structure has been identified. The antigen appears localized in sperm exclusively to perinuclear subacrosomal sites that may be anchored at the male nuclear envelope, given the occurrence of the target epitope in somatic cells as well in nuclear and cytoplasmic sites adjacent to the nuclear membrane.

Selective effect of methoxyindoles on the lymphocyte proliferation and melatonin binding to activated human lymphoid cells.

Three pineal methoxyindoles (melatonin (Mel), 5-methoxytryptamine (5-MTA) and 5-methoxytryptophol (5-MTO)) were studied for their ability to influence the proliferative response of human peripheral blood lymphocytes (PBL) and tonsillar lymphocytes (TL) following activation with concanavalin A (ConA) in vitro. The ConA-stimulated DNA synthesis was affected in a different dose-dependent mode by the methoxyindoles tested. Melatonin and 5-MTO inhibited and 5-MTA increased the ConA-induced [3H]thymidine incorporation in PBL and TL. The initial screening for 2-[125I]iodomelatonin binding using a single point assay revealed significantly increased specific binding to PBL and TL after 72-h stimulation with ConA as compared to the non-activated cell cultures. Coincubation of separate lymphocyte cultures with ConA and Mel or 5-MTO resulted in inhibition of the specific 2-[125I]iodomelatonin binding (85% and 74%, respectively). The specific binding determined in the presence of 5-MTA did not differ from control values. Series of saturation and competition experiments were performed to examine the binding characteristics of ConA-stimulated lymphocytes for 2-[125I]iodomelatonin. The radioligand labelled binding sites of high affinity (Kd = 0.14 +/- 0.03 nM) and low capacity (Bmax = 6.8 +/- 1.5 fM/mg protein). Competitive studies with a variety of indoles determined the following order of relative potency for inhibition of 2-[125I]iodomelatonin binding in TL: 2-iodomelatonin > melatonin > > 5-methoxytryptophol. 5-Methoxytryptamine did not show displacement potency for the labelled ligand. Collectively, our data suggest that pineal hormones might be directly involved in the regulation of the T-lymphoproliferative response of human lymphoid cells. We show the availability of melatonin receptors, which seem to be an intrinsic characteristic of activated human lymphocyte populations. While the effects of Mel and 5-MTO can be linked to the binding sites described, it is unlikely that serotonin agonists like 5-MTA may act through the same sites to influence the mitogen-stimulated lymphocyte proliferation.

Syngeneic anti-idiotypic monoclonal antibodies against an anti-human chorionic gonadotrophin antibody.

Monoclonal antibody designated 1B10 (Mab 1B10) has been shown to be highly specific for the beta-chain of human chorionic gonadotrophin (HCG). We used this antibody to investigate its paratope using anti-idiotypic antibodies. Purified Mab 1B10 has been used to immunize syngeneic BALB/c mice to produce anti-idiotypic monoclonal antibodies. An enzyme immunoassay (ELISA) on Mab 1B10 coated plate was employed to screen the supernatants of growing hybridomas. The specificity of each antibody selected was assessed using an inhibition ELISA and immunoblotting. Monoclonal antibodies belonging to two categories were selected. (a) Those (designated Mab 4F8 and Mab 7G9) recognizing epitopes of the Ig molecule located in/or near the antigen-binding site of Mab 1B10. In ELISA these antibodies were shown to inhibit in a dose-dependent manner, the reaction of Mab 1B10 with its specific antigen; (b) those (Mab 2B8, Mab 3B8) reacting with epitopes located outside of the antigen binding site of the antiHCG antibody molecule and did not influence the reactions of Mab 1B10 and its antigen. Following immunization of syngeneic BALB/c mice monoclonal antibodies (Mab 4F8, Mab 7G9) were produced which recognized epitopes located on the variable region of Mab 1B10 since they did not react with other murine monoclonal antibodies of the same isotype. These antibodies inhibited the binding of Mab 1B10 to its corresponding epitope on the molecule of HCG and they can be defined as syngeneic anti-idiotypic antibodies.

Redistribution of nuclear envelope associated antigen during the mitotic cycle.

Murine hybridomas were generated to DNA/tight binding proteins complex isolated from the residual nuclear structure following a procedure analogous to that yielding "empty" shells of nuclear envelope. A monoclonal antibody designated 2A8 was selected because of its differential immunostaining of mitotic cells of a synchronized mouse fibroblast cell culture L-929. The target antigen was rendered insoluble by a sequence of extractions of isolated nuclei of diverse cell types with detergents, urea, DNase I and alkali thus reproducing some solubility properties of proteins constituting an operationally defined residual nuclear matrix. The cognate polypeptide was localized on a subset of proteins of M(r) 58-65 kDa, 70 kDa in isolated fibroblast nuclear matrices. The functional implication of the antigen in mitosis-related disassembly-assembly process of the nuclear matrix/envelope was detected. At prophase the antibody decorated the nuclear periphery and nuclear envelope fixed inward filaments. A fibrous network of cytoplasmic localization was stained in metaphase. At anaphase the antigen was dispositioned into peripheral fibrogranular clusters of polar orientation predominantly on one side of the nucleus. Proceeding to telophase a spreading fluorescence was manifested over the entire contour of the nuclear periphery to delineate the reforming nucleus. By immunogold electron microscopy of interphase cells the antigen was identified as evenly distributed in chromatin and interchromatin regions. At initiation of chromosome condensation in mitosis the label was detected predominantly in the chromosomal area.

Human hybridomas secreting monoclonal antitreponemal antibodies raised after in vitro stimulation of human lymphocytes.

Peripheral blood lymphocytes from patients with syphilis were stimulated in vitro against Treponema pallidum extract and consequently were fused with mouse myeloma cells to raise heterohybridomas secreting specific human antibodies. In these experiments, 5 heterohybridomas were selected which were shown to secrete monoclonal antibodies which recognized treponemal antigens. Some of the monoclonal (Mab 1C12, Mab 1D11) react with antigens specific to T. pallidum while others (Mab 2A2, Mab 2C8, Mab 2C11) bind to treponemal components which demonstrated group specificity.

Purification and characterization of sperm-coating antigen, identified by a monoclonal antibody.

A procedure was designed for purification of a human seminal plasma-specific antigen (HSP-antigen) identified by a monoclonal antibody produced in this laboratory (mAb 4E6). Pooled human seminal plasma was fractionated by consecutively applied methods: affinity chromatography on Lentil lectin sepharose, gel chromatography on Ultrogel AcA 34 and immunoaffinity on mAb 4E6 coupled CNBr-Sepharose 4B. The antigen-containing fraction obtained after this procedure was proved to be homogeneous when analysed by electrophoresis in polyacrylamide gel. After the consecutive purification procedures the degree of purification was 128 times as compared to the starting material. Electrophoretic analysis of the purified 4E6 antigen under reducing conditions showed that it consisted of 3 polypeptide subunits with molecular weight 70 kDa, 64 kDa and 60 kDa respectively. On the basis of the data obtained from competitive ELISA testing of sera from infertile patients it has been suggested that the identified antigen may be involved in pathogenesis of immunologic infertility.