Failure of sperm-induced immunosuppression: association with antisperm antibodies in women

Immune regulation in the male genital tract

Spermatozoa are not produced until puberty, long after the establishment of tolerance to self-antigens. Therefore, sperm-specific antigens are immunogenic in men. Most men, however, do not produce antibodies to their own gametes. Development of mechanisms to prevent or limit autoimmune responses to spermatozoa were essential for preservation of reproductive capacity. Tight junctions between adjacent Sertoli cells, as part of the blood-testis barrier, prevent sperm-immune cell contact. In some portions of the genital tract this barrier is thin or incomplete. Immune mechanisms have evolved to actively suppress the autoimmune response to spermatozoa within the genital tract. Unlike in the circulation where CD(4+) helper T lymphocytes predominate, CD(8+) suppressor/cytotoxic T lymphocytes are the most prominant T cells in the epididymis and vas deferens. In addition, spermatozoa suppress pro-inflammatory lymphocyte immune responses, possibly by inducing production of anti-inflammatory cytokines. Antisperm antibody production is induced in the male genital tract when a local infection or disruption in the genital tract physical barrier leads to an influx of CD(4+) T cells. In response to induction of a productive immune response, two additional mechanisms downregulate humoral immunity within the genital tract. T lymphocytes possessing the gammasigma form of the antigen receptor (gammasigma T cells) are concentrated in the male genital tract and in semen. These cells become activated and proliferate in men with evidence of sperm autoimmunity. Activated gammasigma T cells inhibit production of antibodies by activated B lymphocytes, thereby limiting antisperm antibody production. Heat shock proteins (hsps) are also present in semen in association with infection and antisperm antibody formation. Hsp gene transcription leads to inhibition of transcription of the genes coding for pro-inflammatory cytokines and, conversely, to activation of gammasigma T cells. Activated gammasigma T cells also promote hsp synthesis. The mechanisms to inhibit immunity to sperm may hinder effective immune elimination of microoganisms in the male genital tract.

Oxidation of polyamines in human seminal plasma: a possible role in immunological infertility

Sixty-two specimens of seminal plasma obtained from normozoospermic, oligozoospermic, azoospermic, and immunologically infertile males were investigated. The levels of spermine, basal aldehyde, and aldehyde oxidation products were measured, as was the immunosuppressive activity of seminal plasma. No immunosuppressive activity was found in the immunologically infertile group; all other groups showed immunosuppressive activity. The immunologically infertile males showed low aldehyde oxidation products.

Antisperm antibodies: origin, regulation, and sperm reactivity in human infertility

OBJECTIVE

To follow-up and expand discussion on the action mechanisms of antisperm antibodies in human infertility, the etiology and control of antisperm antibody induction, sperm antigens involved in immunoinfertility, and strategies for therapy.

DESIGN

A review of the recent literature with an emphasis on female immunoinfertility.

RESULTS

The role of antisperm antibodies in clinical infertility continues to be defined. Through assisted reproductive technologies, antisperm antibodies were shown to exert detrimental effects on different prefertilization and possibly postfertilization events. The female reproductive tract is part of the common mucosal immune system and is able to mount effective immune responses against infectious agents, foreign antigens, and, occasionally, sperm cells. Sperm membranes and constituents contain numerous antigenic components foreign to the human body, and yet antisperm antibodies become problematic in few women exposed to semen. Semen and sperm cells contain immunosuppressive factors capable of inhibiting different immune cells. Fertile women apparently produce antisperm antibodies but also possess neutralizing serum anti-idiotypic antibodies that are lacking in virgin and immunoinfertile women.

CONCLUSIONS

Antisperm antibodies can affect adversely human fertility but normally may be controlled by anti-idiotypic antibodies, which along with immunosuppressor factors in semen prevent their induction to a significant degree. This balance between detrimental and "beneficial" immune response to sperm may be shifted toward an antisperm antibody response by stimulatory factors such as infection. Therapies may be devised to stimulate the anti-idiotypic antibody system, to induce immune tolerance to sperm antigens, and to use antigens to adsorb antisperm antibodies from spermatozoa.

Activation of circulating gamma delta T-lymphocytes by autologous sperm from men sensitized to sperm

The in vitro proliferative responses to sperm of T-lymphocytes bearing the alpha beta or gamma delta form of the antigen receptor were investigated. Peripheral blood mononuclear cells from five men without antisperm antibodies and eight men with antisperm antibodies both on sperm and in serum were incubated for 72 h in the presence of an equal concentration of autologous live sperm, freeze-thawed sperm and heat-killed sperm. Prior to incubation and after 72 h, aliquots were applied to Teflon coated microscope slides, which were subsequently incubated with monoclonal antibodies to the beta chain and delta chain of the human T-cell receptor. Urethral samples were cultured for bacteria and tested for Chlamydia trachomatis by direct staining and by ELISA. The four men with chlamydial infections had the highest concentrations of circulating gamma delta T-cells (P = 0.0008). The concentration of gamma delta T-cells from men with antisperm antibodies increased 245% over the buffer control in response to live sperm (P < 0.0001). Proliferation of gamma delta T-cells was also seen to a lesser extent in response to freeze-thawed (P = 0.002) and heat killed (P = 0.03) sperm. In contrast, gamma delta T-cells from men without antisperm antibodies proliferated only marginally (36%) in response to live sperm (P = 0.05) and were unresponsive to non-viable sperm. Only from men sensitized to sperm were alpha beta T-cells responsive, to a small extent, to live sperm (P = 0.04). Thus, in men with antisperm antibodies, peripheral gamma delta and alpha beta T-cells appeared to be sensitized to antigens on the surface of viable sperm. The immune response of gamma delta T-cells to sperm may be a useful in vitro system to examine the mechanism of gamma delta T-cell activation.

Enrichment of gamma delta T lymphocytes in human semen: relation between gamma delta T cell concentration and antisperm antibody status

The presence and relative concentrations of T lymphocytes bearing the alpha beta and gamma delta cell receptor (TCR) in human semen were assessed and related to the occurrence of auto-antibodies to sperm in semen and peripheral blood. Using an immunoperoxidase technique, and monoclonal antibodies to the beta chain and delta chain of the human TCR, both alpha beta and gamma delta T cells were detected in each of 30 semen samples examined. In seven men with antisperm antibodies both on their ejaculated sperm and in their serum, the mean concentrations of gamma delta and alpha beta T cells were 3,560 and 3,230 cells/ml semen, respectively. In seven men with antisperm antibodies in serum only, the concentrations of gamma delta and alpha beta T cells were 860 and 1,280 cells/ml, while in 16 men with no evidence of auto-immunity to sperm there was a mean of 350 gamma delta T cells and 610 alpha beta T cells/ml. In contrast, the concentrations of gamma delta and alpha beta T cells in peripheral blood from these same men were unrelated to antisperm antibody status. The mean ratio of alpha beta to gamma delta T cells in peripheral blood of all subjects was 12. The ratio of alpha beta to gamma delta T cells in semen were 0.9 for men with sperm-bound and serum antisperm antibodies, 1.5 for men with antisperm antibodies in serum only and 1.7 for men lacking these auto-antibodies. These results were confirmed by FACS analysis. Thus, gamma delta T cells in human semen comprise a greatly increased proportion of the total T cell population as compared to the circulation. In addition, the relative and absolute concentration of gamma delta T cells are further elevated in semen from men with evidence of localized auto-immunity to their own sperm. These results suggest that gamma delta T cells may function in immune surveillance in the non-sterile proximal portions of the male genital tract and that replication of T cells bearing the gamma delta TCR accompanies an autoimmune response to sperm.

Antisperm antibodies to sperm surface antigens in women with genital tract infection

Antisperm antibodies to sperm surface antigens in nulligravid women with primary upper genital tract infections were measured by the sperm mixed agglutination reaction assay. As many as 56% of women with a primary episode of pelvic inflammatory disease had antisperm antibodies. In addition, 69% of those women with no history of genital tract infection but with laparoscopic evidence of past pelvic infection had significant levels of circulating antisperm antibodies. Electroimmunoblots of sperm preparations probed with the sera of women who had either known or presumed upper genital tract infection revealed a uniformly recognized 69 kd antigen. In contrast, women with circulating antisperm antibodies before primary upper genital tract infection recognized up to five distinct sperm antigen determinants of 27, 54, 131, 146, and 174 kd. It is a distinct possibility that genital tract infections may lead to immunopotentiation of antisperm antibodies that could affect fertility.

Antisperm antibodies in women undergoing intrauterine insemination

Intrauterine insemination is widely used for the treatment of infertility as a result of cervical or male factors or empirically before in vitro fertilization or gamete intrafallopian transfer. This study was designed to confirm or refute the theoretical concern that intrauterine insemination may induce antisperm antibodies in such women. Serum and cervical mucus were obtained at the first, fourth, and sixth intrauterine inseminations. The serum was screened by the Immunobead test for IgG and IgA. If screening results were positive (greater than 10% binding), antisperm antibodies were titered by the microimmobilization and microagglutination tests. The Immunobead test was performed on the cervical mucus after liquefication with bromelin. Ninety-three patients were followed up prospectively. Of these, 40 completed six intrauterine insemination cycles and the remaining 53 completed four cycles. Low transient antisperm antibody levels were detected in 10.8% of the patients and would not be expected to affect the prognosis for fertility. It is concluded that intrauterine insemination does not induce significant antisperm antibody production in women.

Relationship between circulating antisperm antibodies in women and autoantibodies on the ejaculated sperm of their partners

The relationship between antibodies on the surface of ejaculated sperm and circulating antibodies in female partners was evaluated. Of 616 couples examined by the immunobead binding test, there was a 12.4% incidence of sperm-surface antibodies in men whose wives had antisperm antibodies in their sera, but only a 6.5% incidence in partners of women who lacked these antibodies (p less than 0.025). Sperm-bound immunoglobulin G and immunoglobulin A both occurred at a significantly higher frequency (p less than 0.05) in partners of women with serum antisperm antibodies. Increased incidence of both immunoglobulin G (p less than 0.01) and immunoglobulin M (p less than 0.005) circulating antisperm antibodies in females were observed when the male partners had antibody-bound sperm. Antibody-coated sperm may activate lymphocytes in the female partners after coitus, thus leading to the production of antisperm antibodies. This may be an additional mechanism that leads to female isoimmunity to sperm and infertility.

Association between recurrent spontaneous abortions and circulating IgG antibodies to sperm tails in women

The isotype and regional specificity of antisperm antibodies in the circulation of women with recurrent spontaneous abortions was examined. There was a statistically significant association (P less than 0.005) between the presence of IgG tail-directed antisperm antibodies and a history of unexplained recurrent spontaneous abortion. These antibodies were detected in 36.4% of 44 women with recurrent abortions and 14.6% of 616 female partners of infertile marriages. In contrast, no differences in IgG sperm head-directed antibodies or in IgA and IgM antisperm antibodies were observed between the two groups. Husbands of women in the miscarriage or infertile groups had similar semen evaluations. Antisperm antibodies may be a marker for defective immunosuppression in women with recurrent miscarriages. Alternatively, exposure of sperm-sensitized pregnant women to sperm may activate the maternal immune system to respond to paternal antigens present on the embryo.