Vasectomy-induced autoimmunity: antisperm and antinuclear autoimmune monoclonal antibodies

Characterization of a spontaneously occurring self-reactive antibody against sperm in mice

We previously established a spontaneously occurring monoclonal antibody, namely Ts3, that was reactive to sperm from an aged male mouse. The present study investigated the characteristic properties and reproductive functions of Ts3. Immunofluorescent staining revealed that Ts3 reacted to epididymal sperm, and the corresponding antigen was located in the midpiece and principal piece. Immunohistochemistry revealed positive reactions in the germ cells and Sertoli cells in the testis, the epithelial cells in the epididymis and vas deferens. Through western blotting with two-dimensional electrophoresis, we demonstrated that Ts3 reacted with four spots, which were around Mr ∼25,000-60,000 and pI 5-6. MALDI-TOF/TOF mass spectrometry identified outer dense fiber 2 (ODF2) as a candidate for Ts3. ODF2 is a cytoskeletal structural component located in the midpiece and principal piece of the flagella of mammalian sperm. This was validated with the result of immunofluorescent staining, suggesting that ODF2 was the main target antigen for Ts3. Sperm immobilization test showed that Ts3 possessed sperm immobilizing activity. Furthermore, Ts3 impaired early embryo development but not in vitro fertilization. These results suggest that ODF2 plays an important role in both sperm function and early embryonic development.

Developmental ontogeny of autoantigens associated with localized autoimmunity in murine testis and epididymis

Experimental autoimmune orchitis (EAO) with experimental autoimmune epididymitis (EAE) can be induced in mice by immunization with testicular antigens emulsified in adjuvants. On immunization with syngeneic testicular germ cells (TGC) alone, EAO with no EAE is induced in mice. Recently, we found that EAE with no EAO can be induced in vasectomized mice by immunization with TGC. In the present study, we investigated the appearance of autoantigens relevant to EAO and EAE by reacting each immune serum sample with testes and epididymides extracts from normal mice of various ages by immunoblotting. The results showed that the antisera obtained from mice with EAO lesions specifically defined testicular antigens with molecular weights of 15 kDa, 40 kDa, 75 kDa and >200 kDa from 4 weeks of age, but the antisera obtained from mice with EAE strongly defined both testicular and epididymal antigens of 25 kDa from 5 and 8 weeks of ages, respectively. These results suggest that vasectomy changes the target autoantigens in TGC-induced autoimmunity.

Identification of post-vasectomy sperm auto-antigens in fox (Vulpes vulpes) by two-dimensional gel electrophoresis and Western blotting

The aim of this work was to identify antigenic surface proteins on fox spermatozoa. Six foxes were inguitinally vasectomised, and the time course of antibody response in the sera was studied. Five out of the six foxes reacted to vasectomy with a production of antisperm antibodies. The number of bands recognised by Western blot was maximal 120-150 days after the vasectomy, at the end of the reproductive season. On the whole, 30 bands were recognised between 9 and 150 kDa. The pattern of recognised proteins varied from one fox to another. The humoral response was studied in one fox 2 years after the vasectomy, before, during and after the breeding season. The same proteins were recognised, but the intensity of staining was increased during the testis regression. Using FITC-labelling on sperm smears with fox sera, antigens were localised at or near the sperm surface, either on the acrosome or both on the acrosome and on the flagellum. Using two-dimensional gel electrophoresis and Western blotting, we identified eight areas containing major antigens, recognised by at least two sera. The molecular weights (kDa) and isoelectric points of the repeated antigens were, respectively [150, 6.6-6.0]; [105-98, 6.0-5.5]; [97, 4.6-4.3]; [95, 5.0]; [85-80, 5.4-5.1]; [42, 5.0-4.8]; [17-15, 6.5-5.9]; and [17-15, 5.5-4.8]. The results of this study can be used to characterise more precisely fox sperm auto-antigens by microsequencing the selected proteins.

A novel approach to the generation of antibodies against phylogenetically preserved sperm antigens

Conventional methods for immunization of laboratory animals against human spermatozoa proved not to be efficient enough to identify phylogenetically conserved sperm-specific antigens. A combination of vasectomy and subcutaneous administration of autologous testis homogenates was tested in 5 New-Zealand rabbits, and in 7 Long-Evans and 8 Spraque-Dawley rats in an attempt to induce an autoimmune response against such antigens. This experimental procedure resulted in a generation of sperm autoantibodies cross-reactive with human, rabbit and rat spermatozoa, as demonstrated by sperm-agglutination, ELISA and flow cytometry (FCM). No specific binding to human seminal plasma was detected by ELISA, indicating that intrinsic sperm membrane antigens rather than sperm-coating antigens were involved in establishing cross-reactivity with human spermatozoa. This suggestion was confirmed by the finding that rabbit autoantisera reacted more strongly against epididymal than against ejaculated human spermatozoa as shown by FCM. Humoral antispermatozoal response correlated well with impaired spermatogenesis in rabbits. The autoimmunized rats revealed severe alterations in reproductive tissues, including testicular and epididymal sperm granulomas; however, they showed a lower incidence of circulating antibodies. The results indicate that the established experimental model in rabbits can be further used to identify and characterize evolutionary preserved intrinsic sperm membrane autoantigens, which are desirable candidates for contraceptive vaccine development.

Characterization of autoantigens relevant to experimental autoimmune orchitis (EAO) in mice immunized with a mixture of syngeneic testis homogenate and Klebsiella O3 lipopolysaccharide

Experimental autoimmune orchitis (EAO) in mice has been induced by repeated injection of a mixture of syngeneic testis homogenate and Klebsiella O3 lipopolysaccharide (KO3 LPS) as a potent adjuvant. The antisera obtained from mice with EAO lesions defined several antigens with apparent molecular weights (MW) of 38,000 (38 kd), 86 kd, 100 kd, and greater than 200 kd by the immunoblotting method. These antigens were organ-specific and exclusively present on the acrosome of spermatozoa, suggesting that these acrosomal antigens were highly relevant to EAO. It was found that the antigen with a fairly high MW (greater than 200 kd) was expressed on spermatozoa from the epididymis. Furthermore, the acrosomal 86 kd antigen was predominantly expressed in the testis, while the 100 kd antigen was dominant in the spermatozoa from the epididymis. It was therefore suggested that the 86 kd and 100 kd antigens in the acrosome were differentially expressed on the process of maturation of spermatozoa.

Vasectomy-induced autoimmunity: monoclonal antibodies affect sperm function and in vitro fertilization

A panel of sperm-reacted monoclonal auto-antibodies developed from spleen cells of vasectomized mice (BDF1) were characterized. Immunogenic antigens were mainly located on the acrosome, midpiece and principal piece. All of the monoclonals were IgM; three demonstrated a multispecific reaction with testis and/or epididymis antigen extracts by immunoblotting. Immunobead studies indicated that most of the antibodies were to surface molecules, a finding supported by the observation that five of the seven antibodies caused complement-mediated immobilization (although not sperm agglutination) of mouse sperm. In vitro fertilization was significantly impaired when antibodies (Vx5, 8 and 10) were added to the sperm prior to exposure to the eggs. Furthermore, passive immunization with Vx5 antibody reduced in vivo fertilization. Our findings indicate that vasectomy-generated antibodies can reduce sperm function in vitro and in vivo.

Autoantibodies and common idiotypes in men and women with sperm antibodies

Antisperm antibodies have been implicated as a causative factor of infertility and pregnancy wastage. Since concomitant autoimmune phenomena were reported in men with antisperm antibodies, we investigated known antisperm antibody-positive sera from 25 women, 27 men, and the respective seminal plasma samples. The investigated autoimmune panel included a search for antinuclear antibodies, autoantibodies (in IgG, IgM and IgA isotypes) to seven phospholipids (cardiolipin, phosphatidylserine, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid), to four histone subfractions (H1, H2A, H3, H4), and to four polynucleotides [ssDNA, dsDNA, poly(I), and poly(dT)], total immunoglobulin levels, and sperm antibody titers. The sera were also evaluated for the presence of a common anti-deoxyribonucleic acid antibody, and anticardiolipin antibody idiotypes. Levels of sperm antibody titers were significantly lower in women than in men. Both men and women with antisperm antibodies demonstrated elevated total IgG levels compared with those of normal control subjects. Only women showed elevated levels of total IgM. Sera from 24% of women and 11% of men with antisperm antibodies demonstrated antinuclear antibody titers greater than 1:40. The most striking autoantibody abnormalities were found among antiphospholipid antibodies. Sera from women with antisperm antibodies demonstrated higher autoantibody production than was found in their male counterparts. A significant correlation was found between antisperm antibodies and IgM anticardiolipin and IgA anti-phosphatidylinositol in women and between sperm antibodies and IgA phosphatidylserine antibodies in men. The presence of anticardiolipin and anti-deoxyribonucleic acid antibody idiotypes was significantly more frequent in women than in men. By means of discriminant analysis and variables selected by this mathematical model, the identification of 24 of 25 women and 26 of 27 men with antisperm antibodies was correctly predicted. These results suggest that women and men respond differently to sperm antigens. The apparent cross-reactivity between sperm antibodies and other autoantibodies, usually associated with autoimmune disease, suggests that a polyclonal B cell activation, similar to that seen in autoimmune diseases, occurs in patients with sperm antibodies.

Occurrence of sperm antibodies in adult rats after prefertile traumatic vas lesions

The occurrence of sperm antibodies has been studied in adult rats, which at prefertile age had been subjected to unilateral vasectomy, unilateral or bilateral crush injury of the vas or bilateral resection of the ductal artery. By means of indirect immunofluorescence technique, circulating sperm antibodies could be demonstrated in the blood in all groups 13 weeks postoperatively: unilateral vasectomy 15/17 (88%), unilateral crush injury 14/20 (70%), bilateral crush injury 13/20 (65%) and vascular injury 14/20 (70%). Sperm granulomas were observed in the unilateral vasectomy group (14/17) and in the bilateral crush injury group (4/20), whereas no sperm granulomas were seen in the unilateral crush injury or the vascular injury group.