Human sperm chaperone HSPA2 distribution during in vitro capacitation.

Human fertilization success depends on the ability of the spermatozoa to undergo capacitation. Even though this process can be conducted in vitro, the optimal time for a sperm cell to complete capacitation in vitro is still under discussion due to the lack of proper capacitation biomarkers. Here, we evaluated the influence of in vitro capacitation time on HSPA2 distribution over human sperm head testing this chaperone as a potential capacitation biomarker. The chaperone was assessed in human spermatozoa from 16 normozoospermic donors using indirect immunofluorescence in uncapacitated, one and four-hour capacitated spermatozoa. The percentage of HSPA2 immunofluorescent cells before and after one hour of capacitation did not differ significantly. However, after four hours of capacitation, we observed a significantly higher percentage of HSPA2 labelled cells. In fluorescent cells analysed before capacitation, we could not identify a predominant distribution pattern. Meanwhile, after capacitation, most sperm showed a highly labelled equatorial band accompanied by a homogeneous fluorescence throughout the acrosomal region. Our findings suggest that HSPA2 needs more than one hour of in vitro capacitation for being correctly distributed in the anterior region of the sperm head. In conclusion, the present study provides solid evidences for the utility of HSPA2 as a biomarker of human sperm in vitro capacitation. Due to its importance during egg-sperm recognition, the use of HSPA2 as a biomarker before an artificial reproduction technique may be suggested, in addition to a longer capacitation time during sperm preparation.

Human sperm DNA damage has an effect on immunological interaction between spermatozoa and fallopian tube.

BACKGROUND: Toll-like receptors play a crucial role in the immunological interaction between the spermatozoa and fallopian tube and contribute to the ovulation, sperm capacitation, fertilization, and pregnancy. OBJECTIVES: To investigate the expression of toll-like receptors and their adaptor molecules and cytokines under the effect of spermatozoa with high DNA fragmentation (high DF) in human fallopian tube cell line (OE-E6/E7) and compare to those in normal spermatozoa. MATERIALS AND METHODS: Fresh semen samples were obtained from 10 unexplained infertile males with high DF (more than 20%) and from 10 healthy donors with a DF less than 3%. After sperm preparation, samples were co-cultured with OE-E6/E7. Toll-like receptors, myeloid differentiation factor 88 (MyD88), TIR domain-containing adapter protein (TIRAP), TIR domain-containing adapter-inducing IFN-b (TRIF), TRIF-related adapter molecule as well as IL-6, IL-8, IFN-ß, and TNFα mRNA expression were evaluated by quantitative real-time PCR. Protein levels of these cytokines and chemokines were measured using ELISA method. RESULTS: TLR 1-6 mRNA expression in OE-E6/E7 was significantly higher under the effect of spermatozoa with high DF compared to the spermatozoa with low DF. Furthermore, significantly increased mRNA expression of MyD88, TIRAP, and TRIF was observed in the high DF group compared to the low DF group, except TRIF-related adapter molecule. Moreover, the expression of IL-6 and IL-8 in the high DF group was significantly higher than low DF group, although there was no significant difference in IFN-ß and TNFα expression between the groups. DISCUSSION AND CONCLUSION: Damage-associated molecular patterns from DNA damage activate TLR signaling pathway in human fallopian tubes and result in the upregulation of inflammatory cytokines and chemokines. This situation may provide pathologic environment for capacitation, fertilization, embryo development, and implantation in female reproductive tract and can be one of the mechanisms of infertility in men with high DF.

Sperm-bound antisperm antibodies prevent capacitation of bovine spermatozoa.

It was hypothesized here that sperm-bound antisperm antibodies (ASAs) impair the ability of bovine spermatozoa to undergo capacitation, bind to the zona pellucida, and complete the acrosome reaction. The effect of ASA binding on these functions was evaluated in frozen/thawed spermatozoa from four bulls before and after induction of ASAs. Ejaculates were divided into ASA negative (<10% immunoglobulin [Ig]G- and IgA-bound spermatozoa) or ASA positive (≥20% IgG and/or IgA-bound spermatozoa). The percentage of capacitated (Merocyanine 540 positive) live spermatozoa in response to heparin was lower in ASA-positive than ASA-negative ejaculates (P < 0.0001). Treatment with heparin resulted in a higher percentage of capacitated spermatozoa compared with control treatments in ASA-negative but not ASA-positive ejaculates. The percentage of capacitated spermatozoa after heparin treatment was negatively correlated with IgA (P = 0.02, R2 = -0.48) but not IgG binding. Sperm binding to the zona pellucida was lower in IgA-positive (six spermatozoa/oocyte; 3-10 spermatozoa/oocyte) than IgA-negative ejaculates (seven spermatozoa/oocyte; 4-13 spermatozoa/oocyte) (P = 0.019). Zona binding was negatively correlated with the percentage of IgA-bound spermatozoa (P = 0.04; R2 = -0.24) but not IgG-bound spermatozoa. The percentage of acrosome-reacted spermatozoa was higher in calcium ionophore A23187-treated than control aliquots in both ASA-negative and ASA-positive ejaculates (P < 0.0001). However, the percentage of acrosome-reacted spermatozoa did not differ between ASA-positive and ASA-negative samples, and no correlation was identified with IgG or IgA binding. It was concluded that sperm-bound IgA affected the ability of bovine spermatozoa to undergo capacitation. ASAs inhibited the changes in plasma membrane fluidity associated with capacitation and binding of spermatozoa to the zona pellucida.

Effect of immunization against prostate- and testis-expressed (PATE) proteins on sperm function and fecundity in the rat.

Evaluating the immunocontraceptive potential of sperm-bound proteins is an active area of investigation. In this study, we analyzed the role of prostate- and testes-expressed (PATE) and PATE-F proteins in sperm function. Capacitation was measured as a function of tyrosine phosphorylation of sperm membrane proteins. Ionophore-induced acrosome reaction was assessed by measuring the fluorescence intensity of calcium-bound Fluo 3-AM and sperm-bound PNA-FITC in a flow cytometer. Rat spermatozoa subjected to capacitation and acrosome reaction in vitro displayed changes in the PATE and PATE-F protein localization on their surface, indicating the role of these proteins in sperm function. Capacitation and ionophore-induced acrosome reaction in vitro were inhibited in spermatozoa pre-incubated with antiserum raised in rabbit against PATE or PATE-F. Male rats were immunized with PATE proteins to assess their role in sperm function and fecundity. Antibody titer in the serum, testicular, and epididymal fluid was measured by ELISA. The motility parameters were recorded using CASA. High antibody titer was observed in serum, epididymal, and testicular fluid in rats immunized with PATE or PATE-F protein. Immunization did not cause any structural damage and inflammation in the testis and epididymis. PATE and PATE-F antisera obtained from the immunized rats inhibited acrosome reaction. Motility parameters, capacitation, acrosome reaction, and fecundity were compromised in PATE-F-immunized rats, whereas the same were not affected in rats immunized with PATE. These results suggest that PATE-F might play an important role in sperm function and fecundity and can be explored further to determine its immunocontraceptive potential.

Effects of autoimmunity to the prostate on the fertility of the male rat.

OBJECTIVE: To study the putative direct consequences of autoimmunity to the prostate on male semen quality and fertility potential. DESIGN: Experimental animal study. SETTING: Immunology, CIBICI-CONICET, National University of Cordoba, Argentina. ANIMAL(S): Twelve male and 24 female Wistar rats. INTERVENTION(S): Autoimmune prostatitis was induced following a standard protocol. MAIN OUTCOME MEASURE(S): Citric acid, zinc, sperm vitality, reactive oxygen species levels, total antioxidant capacity, DNA fragmentation, and lipid peroxidation were analyzed in semen samples. Mating studies were also performed, and different fertility parameters (potency, fecundity index, fertility index, fetus size, and preimplantation and postimplantation embryo loss) were assayed. RESULT(S): Citric acid and zinc levels were decreased in seminal samples from autoimmune rats. Increased reactive oxygen species values and lower levels of total antioxidant capacity were shown in semen samples from autoimmune animals. Moreover, decreased levels of sperm vitality, high percentages of damaged DNA sperm cells, and elevated lipid peroxidation levels also were shown in semen from autoimmune rats. A significant decrease in the fertility index and augmented percentages of embryo loss were observed in the autoimmune group. CONCLUSION(S): An autoimmune response to the prostate impairs its functionality and induces important alterations in seminal oxidative balance, producing higher levels of lipid peroxidation and sperm DNA damage. Moreover, autoimmunity to the prostate gland seriously compromises male fertility.

Pathogenic consequences in semen quality of an autoimmune response against the prostate gland: from animal models to human disease.

We have recently proposed an autoimmune etiology in approximately 35% of chronic nonbacterial prostatitis patients, the most frequent form of prostatitis observed, because they exhibit IFN-gamma-secreting lymphocytes specific to prostate Ags. Interestingly, this particular group of patients, but not the rest of chronic nonbacterial prostatitis patients, also presented striking abnormalities in their semen quality. In this work, we use an experimental animal model of autoimmune prostatitis on Wistar rats developed in our laboratory to investigate when, where, and how sperm cells from autoimmune prostatitis individuals are being damaged. As in patients, a marked reduction in sperm concentration, almost null sperm motility and viability, and an increased percentage of apoptotic spermatozoa were detected in samples from animals with the disease. Prostate-specific autoantibodies as well as elevated levels of NO, TNF-alpha, and IFN-gamma were also detected in their seminal plasma. In contrast, epididymal spermatozoa remain intact, indicating that sperm damage occurs at the moment of joining of prostate secretion to sperm cells during ejaculation. These results were further supported by experiments in which mixture of normal sperm cells with autoimmune seminal plasma were performed. We hypothesize that sperm damage in experimental autoimmune prostatitis can be the consequence of an inflammatory milieu, originally produced by an autoimmune response in the prostate; a diminished prostate functionality, evidenced by reduced levels of citric acid in semen or by both mechanisms simultaneously. Once more, we suggest that autoimmunity to prostate may have consequences on fertility.

Study on the role of a sperm membrane-associated antigen in canine fertilization.

The Mab 4B12 produced by us against capacitated boar spermatozoa was found to recognize a protein located in the acrosome portion of capacitated boar spermatozoa which is shared by different animal species, dogs included. It was shown that Mab 4B12 might affect fertilizing ability in vitro of boar spermatozoa. Using indirect immunofluorescence (IIF) test, we provide evidence here that Mab 4B12 stained the acrosome of the capacitated but not of the ejaculated and acrosome-reacted canine spermatozoa. The biological experiments using hemizona assay functional test in this study provide evidence supporting the involvement of Mab 4B12 corresponding antigen in the functional steps required for canine sperm-zona pellucida binding. These results together with the data on cell and tissue specificity of the 4B12 antigen suggest its contraceptive potential for canine fertilization.

Further characterization of reproductive abnormalities in mCd59b knockout mice: a potential new function of mCd59 in male reproduction.

CD59 is a GPI-linked membrane protein that inhibits formation of the membrane attack complex of complement. We reported recently that mice have two CD59 genes (termed mCd59a and mCd59b), and that the targeted deletion of mCd59b (mCd59b-/-) results in spontaneous hemolytic anemia and progressive loss of male fertility. Further studies of the reproductive abnormalities in mCd59b-/- mice reported in this study revealed the presence of abnormal multinucleated cells and increased apoptotic cells within the walls of the seminiferous tubules, and a decrease in the number, motility, and viability of sperm associated with a significant increase in abnormal sperm morphologies. Both the capacitation-associated tyrosine phosphorylation and the ionophore-induced acrosome reaction as well as luteinizing hormone, follicle-stimulating hormone, and testosterone serum levels were similar in mCd59b-/- and mCd59b+/+. Surprisingly, the functional deficiency of the complement protein C3 did not rescue the abnormal reproductive phenotype of mCd59b-/-, although it was efficient in rescuing their hemolytic anemia. These results indicate that the male reproductive abnormalities in mCd59b-/- are complement-independent, and that mCd59 may have a novel function in spermatogenesis that is most likely unrelated to its function as an inhibitor of membrane attack complex formation.

Monoclonal antibody from vasectomized mouse identifies a conserved testis-specific antigen TSA70.

Vasectomy results in the occlusion of testicular outflow, leading to autoimmunity characterized by the production of antisperm antibodies (ASA). Reports on the rise in ASA following vasectomy in several species are available; however, not much is known about the specific sperm autoantigens to which postvasectomy antibodies are directed. In the present study, monoclonal antibodies were generated using a vasectomized mouse. One of the monoclonal antibodies, D5E5, identified an approximately 70-kd antigen localized on the principal piece of the tail and also on the tip of the acrosome of mouse sperm. The cognate antigen was expressed postmeiotically in a stage-specific manner during spermiogenesis, starting from step 8 of elongating spermatids during spermiogenesis up to mature spermatozoa. The protein was conserved across the species, as observed by its presence in rat, bull, marmoset, and human sperm. Following capacitation, the antigen on the head was seen to shift to the acrosomal region and was lost after the acrosome reaction. However, the localization on tip of the acrosome still persisted, which indicates that the antigen may play a role post-acrosome reaction in sperm egg interaction. Resistance to Triton X-100 solubilization indicates that TSA70 could be an acrosomal matrix protein. In addition, we observed a significant reduction in forward progressive motility of mouse sperm treated in vitro with D5E5. In view of its testis specificity, acrosome and tail localization, and conserved nature, TSA70 is likely to play an important role in sperm function.

Clinical associations and mechanisms of action of antisperm antibodies.

OBJECTIVE: To review and critique the current English literature describing the effects of antisperm antibodies (ASA) on mammalian fertility. DESIGN: A comprehensive English language literature was searched using Medline and by hand-searching. Emphasis was placed on clinically relevant articles. RESULT(S): Results from the studies were extrapolated and the effects of ASA on fertility described. CONCLUSION(S): Antisperm antibodies may interfere with fertility. Not all ASA cause infertility. Current tests cannot differentiate the infertility-related ASA from those that do not interfere with infertility, because the antigenic specificities of these ASA are not known. The antigens which the infertility-related ASA must be characterized to allow an accurate detection and proper treatment for couples with ASA.

Sperm-immobilizing antibodies block capacitation in human spermatozoa.

Sperm-immobilizing antibodies block human fertilization by interfering with the acrosome reaction (AR). To clarify the mechanism of blockage of AR by sperm-immobilizing antibodies, the authors examined their effects on the increase of intracellular free Ca2+ concentration induced by follicular fluids (Ca2+ influx) in spermatozoa and on their capacitation. Sperm-immobilizing antibodies did not suppress Ca2+ influx induced by follicular fluid, but they inhibited capacitation of human spermatozoa. Namely delta%AR (%AR after addition of an AR inducer--%AR before treatment) induced by progesterone was significantly (p < .0001) lower when spermatozoa were incubated in human tubal fluid medium cotaining antibody-positive serum (1.2%), compared to that when incubated in control medium (19.2%). Furthermore, the proportion of both spermatozoa that became capacitated and ones that had become capacitated decreased significantly (p < .0001) after 2, 4, and 6 h of incubation in medium containing antisperm antibody-positive serum, compared to those of spermatozoa incubated in control medium. In conclusion, sperm-immobilizing antibodies may be closely related to their blockage of capacitation.

Antibodies to human sperm YLP12 peptide that is involved in egg binding inhibit human sperm capacitation/acrosome reaction.

Recently, the authors reported a novel dodecamer peptide sequence, designated as YLP12 on human sperm, that is involved in binding to zona pellucida (ZP) of human oocyte [10]. This unique sequence is present on the acrosomal region of the human sperm cell and is expressed only in human testis/ sperm. The aim of the present study was to examine whether YLP12 sequence is involved in capacitation/acrosome reaction. Swim-up sperm were capacitated with anti-YLP12 Fab' antibodies or control Fab's (40 and 85 microg/mL) and then the acrosome reaction was induced with calcium ionophore. An average of 64-73% sperm underwent acrosome reaction when they were capacitated in the presence of 40-85 microg/mL of bovine serum albumin or control Fab's. A significant (p < .01 to < .001) reduction (58-75%) in the percentage of acrosome-reacted sperm was observed when the sperm were capacitated in the presence of YLP12 Fab's. These data indicate that the YLP12 peptide sequence is involved in sperm capacitation / acrosome reaction, and may find clinical applications in the diagnosis and treatment of male infertility and immunocontraception.

Anti-mouse sperm monoclonal antibody, A-1, inhibits sperm capacitation, acrosome reaction and calcium influx into spermatocytes.

An anti mouse sperm monoclonal antibody (A-1) inhibited sperm penetration into the egg zona pellucida and bound to an acrosomal area of sperm. In this study, we examined whether or not the antibody affects the sperm capacitation and the acrosome reaction. Sperm were incubated in modified Krebs-Ringer bicarbonate medium in the presence or absence of the antibody. The capacitation of sperm was assessed by chlortetracycline fluorescence pattern assay. The percentage of capacitated sperm did not increase in the presence of antibody, but increased time-dependently in its absence. The acrosome reaction of the capacitated sperm was induced by the addition of ionophore. The ionophore, however, failed to induce the reaction in the presence of the A-1 antibody. Next, the calcium influx into spermatocytes was examined. The capacitated sperm, preloaded with Fura-2, were treated with ionomycin in the presence or absence of the A-1 antibody. The influx of calcium ions into capacitated spermatozoa was also inhibited by the antibody. Thus a monoclonal antibody, A-1, inhibited the sperm capacitation, acrosome reaction and calcium influx into spermatocytes.

Antibody against 28-kDa intra-acrosomal sperm protein as a tool for evaluation of acrosomal integrity in bull spermatozoa.

Monoclonal antibody ACR.4 recognizing specifically the 28-kDa intra-acrosomal protein was prepared by immunization of mice with acetic acid extract of boar spermatozoa, but cross-reacted also with bull intra-acrosomal protein. This monoclonal antibody was used for immunostaining analysis of bull spermatozoa before and during capacitation and ionophore-induced acrosome reaction. Immunostaining analysis showed changes of 28-kDa protein in the acrosome during capacitation and loss of this protein after induced acrosome reaction by ionophore A23187. Therefore, this monoclonal antibody can be used in the bull spermatozoa as an immunological test for detection of the acrosome state after manipulation with spermatozoa or after freezing/thawing. This test could be useful (apart from morphology and motility) for the selection of suitable spermatozoa for insemination or in vitro fertilization.

Monoclonal antibodies reacting against capacitated but not with freshly ejaculated boar spermatozoa.

PROBLEM: The involvement of individual sperm proteins in differentiation of antigenically specific and functionally defined regions on sperm membrane has not yet been completely elucidated. METHOD: BALB/c mice were immunized with live capacitated boar spermatozoa and used for production of monoclonal antibodies (MAbs). ELISA, IIF, SDS-PAGE, IVF, and cytologic methods were used for selection and biological characterization of MAbs as well as for identification of corresponding antigens. RESULTS: MAb1F10, MAb2E2, and MAb4B12 react with antigens in the acrosome portion of live capacitated spermatozoa, MAb 1F10 reacted with human sperm cells along with those from bull, ram, mouse, dog, whereas MAb2E2--with mouse's spermatozoa and MAB4B12-with bull's, mouse's, and dog's spermatozoa. Some glycolytic enzymes seemed to reduce mildly the reactions of the MAbs with enzyme treated sperm cells; proteolytic enzymes eliminated the binding of MAbs to the sperm acrosome. These MAbs have no sperm agglutinating and/or sperm-immobilizing activities and reduced the number of spermatozoa binding to zona pellucida. CONCLUSIONS: MAb1F10, MAb2E2, and MAb4B12 seemed to recognize membrane associated antigens with potential role in the initial stages of fertilization, specific for capacitated but not for freshly ejaculated spermatozoa.

Effect of sperm-agglutinating antibodies on sperm capacitation and acrosome reaction.

OBJECTIVE: To study the effect of polyclonal/monospecific antisera on sperm agglutination versus capacitation as well as acrosome reaction. MATERIALS AND METHODS: Swim-up spermatozoa from cauda epididymides of fertile male hamsters were incubated under liquid paraffin with polyclonal/monospecific antisera obtained from immunized BALB/C mice, as well as with normal serum from control BALB/C mice, at various dilutions. RESULTS: The anti-sperm antibodies caused a significant (P < .05) sperm agglutination of various types of dilutions below 1:1000. Both capacitation and true acrosome reaction were inhibited significantly in the spermatozoa incubated with polyclonal/monospecific antisera. Capacitation in the spermatozoa with normal serum started earlier, i.e., at 2 hours of incubation compared to 3 hours of incubation in controls. CONCLUSION: The data differentiate the sperm agglutinating activity from anticapacitation and antiacrosome reaction activity of antisperm antisera at 1:1000 dilution.

Anti-bull sperm monoclonal antibodies: II. Binding changes during capacitation and influence on sperm-zona interactions in vitro.

Anti-bull sperm monoclonal antibodies (mAbs), generated against intra-acrosomal and surface antigens, were evaluated for their functional significance. In experiment I, the influence of mAbs on the bovine sperm-oocyte interaction in vitro was tested on a total of 493 oocytes in either three or four replicate trials. Although the number of sperm bound per zona increased significantly over untreated control samples (23.6 +/- 5.6 vs. 10.0 + 2.4, mean +/- standard error [SE]; P < 0.001) in the presence of one surface-reacting mAb, other mAbs had no effect. Experiment II was designed to determine if the mAbs would detect capacitation-related changes of bull sperm in vitro. Bull sperm were incubated in capacitation medium (supplemented Tyrode's medium [TALP] plus 10 micrograms/ml heparin) for up to 4.5 hours. At 0 and at 4 hours, mAbs in hybridoma culture supernatant were incubated for 30 minutes with sperm, labeled with fluorescein isothiocyanate (FITC)-conjugated secondary antibody, and processed for indirect immunofluorescence assay. Four mAbs specific to intra-acrosomal antigens exhibited a time-dependent increase (P < 0.05) in binding to bull sperm incubated under capacitation conditions. In contrast, the binding of the mAbs specific to surface antigens significantly decreased (P < 0.05) after 4 hours in the presence of heparin. Sperm viability did not change during the 4-hour period. In experiment III, mAbs specific to intra-acrosomal antigens were evaluated to assess bull sperm acrosomal status following lysophosphatidylcholine-induced acrosome reaction. A significant decrease (P < 0.01) in mAb binding following the induced acrosome reaction was observed with all the mAbs; it was highly correlated (r > or = 0.85; P < 0.01) with Pisum sativum agglutinin binding and Giemsa staining. The results suggest that some of the mAbs are potential biological markers for bull sperm surface changes associated with capacitation and the acrosome reaction in vitro.

Fertility studies with antisperm antibodies.

Serum obtained from an infertile subject possessed antibodies that interacted with a human sperm glycoprotein with an estimated M(r) of 17,550 and pI of 5.65 containing 17.7% neutral hexoses and designated as the BS-17 component. Polyclonal antibodies raised against the BS-17 antigen blocked the capacity of human sperm to fertilize zona-free hamster ova in vitro; however, the antibodies did not influence the binding of human sperm to zone-free ova or alter the motility of human sperm. The antibodies inhibited the capacity of mouse sperm to fertilize ova upon in vivo insemination. The BS-17 antigen was detected in human, rat, mouse, rabbit, and hamster sperm by an immunocytochemical method, using polyclonal anti-BS-17 antibodies. Intense staining occurred over the surface of the acrosomal region of all mammalian sperm. The results suggest that the production of anti-BS-17 antibodies contribute to infertility by preventing the capacitation of sperm and/or by blocking the ability of capacitated sperm to fertilize the egg.

Antisperm antibody binding to human sperm inhibits capacitation induced changes in the levels of plasma membrane sterols.

PROBLEM: Human spermatozoa express mannose ligand receptors (MLRs) over the entire head when incubated under conditions that promote loss of free cholesterol. Binding of IgA, IgG, and/or IgM head-directed anti-sperm antibodies (ASAs) to freshly isolated sperm blocks MLR expression in a dose dependent manner. METHODS: Comparison of Western blots of immunoprecipitated glycoproteins from fresh sperm exposed to ASAs from women with those of sperm membrane proteins isolated from capacitated sperm probed with a goat anti-human macrophage MLR antiserum showed that ASAs do not react with human sperm MLRs of 48 and 61 kd apparent molecular weight. RESULTS: The direct effect of ASA binding was to increase membrane free cholesterol content which remained greater than 0.005 mumol/10(9) sperm after 18 h incubations, whereas the sterol content of controls decreased to less than 0.001 mumol/10(9) sperm. Cholesterol addition to sperm inhibited MLR expression in a manner analogous to ASA binding, while increasing temperatures up to the crystalline/liquid-crystalline phase transition for sperm membranes; less than 45 degrees C failed to promote the appearance of MLRs on the surface of fresh sperm. CONCLUSIONS: We conclude that ASA effects on membrane cholesterol content prevent the membrane fluidity changes needed for MLR expression.

Antigens in capacitated spermatozoa eliciting autoimmune responses.

We studied the possible qualitative antigenic differences between native and capacitated spermatozoa pertaining to immunological infertility. Western blot analysis was used to test serum and seminal plasma immunoglobulin G (IgG) from 18 infertile couples with sperm antibodies, and 14 fertile men and 9 fertile women without significant sperm antibodies against native and capacitated spermatozoa from fertile and infertile men. More fertile and infertile subjects had serum and seminal plasma IgG binding to antigens with molecular weights of 34/36, 46, 68, 97, 105, 115, 120, 130, 150 and 190 kDa. in capacitated versus native spermatozoa of all men. Of the other hand, immune reactivity to antigens with molecular weight 22/24, 30, 32, 50, 80, 88/92 and 180 kDa. found in native autoimmune spermatozoa was strongest in infertile couples with sperm antibodies. This reactivity significantly increased against capacitated autoimmune spermatozoa. Native spermatozoa from few fertile men had these antigens but they appeared after capacitation. It seems that certain antigens normally appearing or enhanced after capacitation are already present in native spermatozoa from infertile men, probably due to an inherent aberration or premature capacitation. This might account for the observed enhanced immune responses in infertile couples to sperm antigens from infertile husbands.