Sperm antibodies, immunoglobulins, and complement in human follicular fluid

Deciphering dynamic interactions between spermatozoa and the ovarian microenvironment through integrated multi-omics approaches in viviparous Sebastes schlegelii

The ovarian microenvironment plays a crucial role in ensuring the reproductive success of viviparous teleosts. However, the molecular mechanism underlying the interaction between spermatozoa and the ovarian microenvironment has remained elusive. This study aimed to contribute to a better understanding of this process in black rockfish (Sebastes schlegelii) using integrated multi-omics approaches. The results demonstrated significant upregulation of ovarian complement-related proteins and pattern recognition receptors, along with remodeling of glycans on the surface of spermatozoa at the early spermatozoa-storage stage (1 month after mating). As spermatozoa were stored over time, ovarian complement proteins were progressively repressed by tryptophan and hippurate, indicating a remarkable adaptation of spermatozoa to the ovarian microenvironment. Before fertilization, a notable upregulation of cellular junction proteins was observed. The study revealed that spermatozoa bind to ZPB2a protein through GSTM3 and that ZPB2a promotes spermatozoa survival and movement in a GSTM3-dependent manner. These findings shed light on a key mechanism that influences the dynamics of spermatozoa in the female reproductive tract, providing valuable insights into the molecular networks regulating spermatozoa adaptation and survival in species with internal fertilization.

Sperm Physiological Response to Female Serum-Potential New Insights into the Reproductive Incompatibility Diagnostics

Infertility is assumed to arise exclusively from male- and female-dependent pathological factors. However, recent studies have indicated that reproductive failure may also result from the reproductive incompatibility of the partners. Selection against such incompatibilities likely occurs via female-derived reproductive secretions, including follicular fluid (FF), that mediate gamete-level mate choice towards the sperm of specific males. To facilitate potential development of diagnostic tests for human reproductive incompatibility, we examined whether sperm physiological response to female serum indicate male–female compatibility in the presence of FF. We performed a full-factorial experiment, in which the sperm of 10 males were treated with the FF and serum of 6 healthy females. We found that sperm motility and viability in both biofluids were highly similar and that in 70% of the males, sperm serum treatment predicted male–female compatibility. We also identified male human leucocyte antigen (HLA) alleles and female (FF and serum) anti-HLA antibodies and tested whether the number of allele–antibody matches predict sperm physiological response to female fluids. However, no association was found between measured sperm traits and the number of allele–antibody matches. Overall, the present results may open novel possibilities for the future development of reproductive incompatibility tests and may pave the way towards more accurate infertility diagnostics and treatments.

Mass spectrometry-based glycomic profiling of the total IgG and total proteome N-glycomes isolated from follicular fluid

Couples with infertility issues have been assisted by in vitro fertilization reproduction technologies with high success rates of 50-80%. However, complications associated with ovarian stimulation remain, such as ovarian hyperstimulation. Oocyte quality is a significant factor impacting the outcome of in vitro fertilization procedures, but other processes are also critical for fertilization success. Increasing evidence points to aberrant inflammation as one of these critical processes reflected in molecular changes, including glycosylation of proteins. Here we report results from a MALDI-TOF-MS-based glycomic profiling of the total IgG and total proteome N-glycomes isolated from the follicular fluid obtained from patients undergoing fertilization through either (1) assisted reproduction by modified natural cycle or (2) controlled ovarian stimulation (GnRH antagonist, GnRH Ant) protocols. Significant inflammatory-related differences between analyzed N-glycomes were observed from samples and correlated with the ovarian stimulation protocol used in patients.

Review on autoimmune reactions in female infertility: antibodies to follicle stimulating hormone

Female fertility can be affected by diseases or dysfunctions of reproductive tract, neuroendocrine system, and immune system. Reproductive autoimmune failure can be associated with overall activation of immune system or with immune system reactions specifically directed against ovarian antigens. Majority of the antiovarian autoantibodies are directed against β-subunit of follicle stimulating hormone (anti-FSH). This paper summarizes a current clinical classification of female infertility in the context of general activation of autoimmunity and antiovarian autoimmunity by describing serum anti-FSH. The presence of naturally occurring anti-FSH in healthy women will be discussed. In addition, the putative impairment of ovarian folliculogenesis in case of increased production of those antibodies in infertile women will be characterized.

Sperm surface antigens and the prospects for contraceptive vaccine development

It has been estimated that 500 million couples world-wide have no access to contraception and that approximately 20% of births between 1995 and 2000 will be unwanted. Such statistics have important implications for the rate of world population growth and the possibility of maintaining a sustainable population. Although political change and the empowerment of women across the world will help address these issues, it will also be important to increase the availability of contraceptives; not only the modalities that are in current use, but also novel methods that will satisfy needs that are presently unfulfilled. One such alternative could be a vaccine targeting the human spermatozoon.

Serum allotypes in ovarian follicular fluids of pigs

Sera and ovarian follicular fluids of 158 sows were tested with 27 allotype reagents. Immunodiffusion in agar gel (microtest) and haemagglutination inhibition were used as detection methods. Out of eight 'individual' (Lpb 1,-2,-3,-4,-5,-6,-7,-9) and four 'common' (Lpb 12,-13,-14,-16) specificities of serum beta-lipoproteins (LDL), 11 were present in sera, but none in follicular fluids. On the other hand, Lpr 1 and Lpr (x) allotypes of the VHDL + VLDL beta-lipoprotein system were detected both in sera and in follicular fluids. Of four antigens of the Gp system (Gp A,-a, -B,-b), only the 'dominant' characters, Gp A and Gp B, occurred in the follicular fluid. The typing of polymorphic IgG immunoglobulins (IgG-a or IgG-b system) showed that B1 or A2, B2 or A1 and B3 or A(x) allotypes could be detected both in serum and follicular fluid. Among allotypes that were not yet genetically classified, only the P3 specificity was not found in the population tested. The G1 allotype (preliminarily described as an alpha-globulin) was present in sera only, and the remaining allotypes, G9, P1, P16 and P23 (alpha- or beta-globulins) were present both in sera and follicular fluids. The mechanism of the transmission of serum proteins into ovarian follicles and their possible importance is discussed.

A proteomic analysis of IVF follicular fluid in women <or=32 years old

OBJECTIVE

To address the lack of predictors of IVF success by using proteomic biometrics.

DESIGN

Experimental study of follicular fluid specimens from a prospective cohort of IVF patients.

SETTING

Academic research laboratory and IVF program.

PATIENT(S)

Women <or=32 years old with <11 oocytes retrieved and no pregnancy were matched to women who had >or=11 oocytes and live birth (10 pairs). Year of cycle start and IVF down-regulation protocol were also matched.

INTERVENTION(S)

Follicular fluid was separated by two-dimensional polyacrylamide gel electrophoresis followed by Sypro Ruby staining and comparison with PDQuest software. Logistic regression was incorporated to calculate the likelihood of live birth in relation to the protein spot of interest.

MAIN OUTCOME MEASURE(S)

Protein markers.

RESULT(S)

Liquid chromatography-tandem mass spectrometry and searching of sequence databases revealed 11 potential protein candidates. Haptoglobin alpha, predominantly fetal expressed T1 domain, mitochondrial integrity genome (ATPase), apolipoprotein H (beta-2 glycoprotein I), dihydrolipoyl dehydrogenase, lyzozyme C, fibrinogen alpha-chain, and immunoglobulin heavy chain V-III (region BRO) were found to have increased expression in the live birth group, whereas antithrombin, vitamin D-binding protein, and complement 3 were decreased. An ELISA confirmed a significantly lower level of antithrombin.

CONCLUSION(S)

Proteomic evaluation of follicular fluid is able to identify potential biomarkers of good versus poor responders in matched pairs of IVF patients.

Antisperm antibodies and conception

Sperm have been known to be antigenic for more than a century. There is a strong body of evidence that in humans and in other species at least some antibodies that bind to sperm antigens can cause infertility. Therefore, these antibodies are of interest today for two practical reasons. Firstly, the association of the antibodies with infertility means that they must be detected and then the couples treated appropriately. Secondly, because these antibodies can induce infertility they have the potential to be developed for contraceptive purposes in humans and also for the control of feral animal populations.

Targeted and restricted complement activation on acrosome-reacted spermatozoa

A specific hypoglycosylated isoform of the complement regulator membrane cofactor protein (MCP; CD46) is expressed on the inner acrosomal membrane (IAM) of spermatozoa. This membrane is exposed after the acrosome reaction, an exocytosis event that occurs upon contact with the zona pellucida. We initiated this investigation to assess MCP's regulatory function in situ on spermatozoa. Upon exposure of human spermatozoa to autologous serum or follicular fluid, we unexpectedly observed that acrosome-reacted spermatozoa activated the complement cascade efficiently through C3 but not beyond. Using FACS to simultaneously evaluate viability, acrosomal status, and complement deposition, we found that complement activation was initiated by C-reactive protein (CRP) and was C1q, C2, and factor B dependent. This pattern is consistent with engagement of the classical pathway followed by amplification through the alternative pathway. C3b deposition was targeted to the IAM, where it was cleaved to C3bi. Factor H, and not MCP, was the cofactor responsible for C3b cleavage. We propose that this localized deposition of complement fragments aids in the fusion process between the spermatozoa and egg, in a role akin to that of complement in immune adherence. In addition, we speculate that this "targeted and restricted" form of complement activation on host cells is a common strategy to handle modified self.

Regulation of the mannan-binding lectin pathway of complement on Neisseria gonorrhoeae by C1-inhibitor and alpha 2-macroglobulin

We examined complement activation by Neisseria gonorrhoeae via the mannan-binding lectin (MBL) pathway in normal human serum. Maximal binding of MBL complexed with MBL-associated serine proteases (MASPs) to N. gonorrhoeae was achieved at a concentration of 0.3 microg/ml. Preopsonization with MBL-MASP at concentrations as low as 0.03 microg/ml resulted in approximately 60% killing of otherwise fully serum-resistant gonococci. However, MBL-depleted serum (MBLdS) reconstituted with MBL-MASP before incubation with organisms (postopsonization) failed to kill at a 100-fold higher concentration. Preopsonized organisms showed a 1.5-fold increase in C4, a 2.5-fold increase in C3b, and an approximately 25-fold increase in factor Bb binding; enhanced C3b and factor Bb binding was classical pathway dependent. Preopsonization of bacteria with a mixture of pure C1-inhibitor and/or alpha(2)-macroglobulin added together with MBL-MASP, all at physiologic concentrations before adding MBLdS, totally reversed killing in 10% reconstituted serum. Reconstitution of MBLdS with supraphysiologic (24 microg/ml) concentrations of MBL-MASP partially overcame the effects of inhibitors (57% killing in 10% reconstituted serum). We also examined the effect of sialylation of gonococcal lipooligosaccharide (LOS) on MBL function. Partial sialylation of LOS did not decrease MBL or C4 binding but did decrease C3b binding by 50% and resulted in 80% survival in 10% serum (lacking bacteria-specific Abs) even when sialylated organisms were preopsonized with MBL. Full sialylation of LOS abolished MBL, C4, and C3b binding, resulting in 100% survival. Our studies indicate that MBL does not participate in complement activation on N. gonorrhoeae in the presence of "complete" serum that contains C1-inhibitor and alpha(2)-macroglobulin.

Decay accelerating factor in guinea-pig reproductive organs

Decay accelerating factor (DAF, CD55) expressed in human reproductive organs and gametes is thought to play a pivotal role in protection against autologous complement activation in the genital tract. To further investigate the role of DAF in reproduction, we analysed DAF distribution in reproductive organs using guinea-pigs that express multiple DAF isoforms. In males, significant staining was observed in testis on the elongated spermatids and spermatozoa. Levels of DAF mRNA with a shorter 3' untranslated region were significantly enhanced in testis from 9 weeks of age, indicating the presence of DAF mRNA and protein synthesis of spermatozoa DAF in late haploid germ cells. Epididymal spermatozoa appeared to express DAF on the inner acrosomal membrane as well as over their entire surface. Significant DAF expression was also observed on the epithelium of seminal vesicles from 4 weeks of age, with no increase thereafter in the mRNA. C3 mRNA was not detected in this tissue. In females, DAF was detected on the plasma membranes of oocytes through follicle development and on the apical region of uterine epithelium, although the levels of DAF mRNA in these tissues were low. In addition, DAF was selectively expressed on the apical region of ciliated oviductal epithelial cells. The apical region of the ciliated cells comprising the efferent ductule epithelium was also stained significantly, even at 12 days of age, while other epididymal epithelial cells were hardly stained at any age, suggesting that DAF is constitutively expressed on cilia.

Vaccine for contraception targeting sperm

Development of a vaccine(s) based on sperm antigens represents a promising approach to contraception. The utility of a sperm antigen in immunocontraception is contingent upon its tissue specificity, involvement in fertility and on raising high antibody titer, especially locally in the genital tract, that is capable of inducing reversible infertility. Several sperm antigens, such as lactate dehydrogenase C4, PH-20, sperm protein (SP)-10, fertilization antigen (FA)-1, FA-2, cleavage signal (CS)-1, NZ-1, and NZ-2 have been proposed as potential candidates for the vaccine development. Spermzona pellucida (ZP) binding is a pivotal tissue- and mostly species-specific event in the fertilization process, and the molecules involved in this site constitute the most exciting candidates for immuno-contraception. FA-1 is a sperm-specific glycoprotein having receptor activity for ZP recognition and binding. Complementary DNA encoding for FA-1 antigen has been cloned and sequenced. Active immunization of animals with recombinant FA-1 antigen causes a long-lasting reversible inhibition in fertility by raising a sperm-specific immune response. This antigen is also involved in human immunoinfertility. The exciting findings from the recent trial in immunoinfertile couples indicate that the FA-1 antigen may have clinical application in the treatment of male infertility. A vaccine having most appropriate tissue-specific and effective recombinant and/or synthetic epitopes of various sperm antigens, such as the FA-1 antigen, in a single formulation may provide a highly immunogenic and efficacious antisperm vaccine for contraception. The advances made during the last 5 years suggest that it may be a realistic proposition.

Modulation of integrin function inhibits HIV transmission to epithelial cells and fertilization

Integrin-mediated adhesive interactions are viewed in the context of HIV transmission to susceptible cells and fertilization. The ability of a low-molecular-weight non-peptide integrin modulator to inhibit HIV infection (virus-to-cell and cell-to-cell) and sperm-egg fusion is demonstrated. It is concluded that integrin-modulating substances offer significant promise as female-controlled means for preventing sexual transmission of HIV (whatever entity acts as HIV vector in semen and other penile secretions) and as female-controlled contraceptives.

Complement-inhibiting activity of human seminal plasma and semen quality

Human seminal plasma (SP) contains potent complement inhibitors. This study examined the complement-inhibiting activity of individual SP samples from 118 patients with infertility and analyzed them in relation to various semen parameters. When 25% complement-inhibiting activity was considered the cut off value, less than 1 SD unit from the mean percentage of inhibition of SP samples with normal semen quality, 32 samples (27%) showed low inhibiting activity. Among the lower group, incidences of patients with asthenozoospermia (66%) and oligozoospermia (31%) were significantly (p < .01) higher than those (36 and 10%) in the group whose SP showed significant inhibiting activity. Partial characterization revealed that the component responsible for complement inhibition was heat labile, trypsin resistant, high molecular weight (>10 kD) glycoprotein that can inhibit alternative as well as classical complement pathways. Furthermore, since in the majority of SP samples the anticomplementary activity was blocked by monoclonal antibody against membrane cofactor protein (MCP) or decay accelerating factor (DAF), the complement-inhibiting factors that were identified are likely to be MCP and/or DAF, which are known to be present in human SP. These results suggest that complement-regulatory proteins in SP such as MCP and DAF may protect sperm cells against complement attack in the male reproductive tract.

Expression of complement regulatory proteins on human eggs and preimplantation embryos

PROBLEM

To investigate the relation between the complement system and reproduction, expression of complement regulatory proteins (C3b receptors and inhibitor of the membrane attack complex) were screened on unfixed human eggs and preimplantation embryos.

METHODS

Unfixed unfertilized oocytes and preimplantation embryos obtained from an in vitro fertilization program were stained by indirect immunofluorescence using monoclonal antibodies raised against membrane cofactor protein, (MCP or CD46), decay accelerating factor (DAF or CD55), protectin (CD59), human C3b/C4b receptor (CR1 or CD35), and major histocompatibility complex class I antigen (MHC class I).

RESULTS

CD55 and CD59 were both expressed by the plasma membrane of unfertilized oocytes and pre-implantation embryos. CD46 was not expressed by unfertilized oocytes but appeared at the 6-to-8 cell stage embryo when human gene expression first occurs. CD35 and MHC class I antigens were not expressed at all on oocytes and preimplantation embryos.

CONCLUSIONS

Selective expression of complement regulatory proteins (DAF and protectin) associated with the lack of MHC class I antigens may represent an immune protective mechanism by which human oocytes and preimplantation embryos escape complement-mediated damage during their travel through the female genital tract. Furthermore, participation of these complement regulatory proteins including MCP in cell to cell interaction during fertilization and/or implantation cannot be excluded.

The frequency of antisperm antibodies in the cervical mucus of women with poor postcoital tests and their effect on pregnancy rates

PROBLEM

To determine the impact of the presence of antisperm antibodies (ASAs) in the cervical mucus of female partners in couples with unexplained poor postcoital tests (PCT). Furthermore, the efficacy of intrauterine insemination (IUI) in these same patients was determined by pregnancy rates (PRs).

METHOD

Pregnancy rates following IUI in patients with infertility and poor postcoital tests, whether the cervical mucus was positive or negative for ASAs, were evaluated.

RESULTS

The 6-month PRs were similar in the ASA negative (40.5%) versus the positive (42.4%) group.

CONCLUSIONS

It appears that the antifertility effect of ASA may be mainly the immobilization of sperm in the cervical mucus, and thus, performing IUI may effectively correct the problem.

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.

The value of routine screening of female serum for antisperm antibodies in assisted reproductive technology cycles

OBJECTIVE

To determine the effect of antisperm antibodies in the female serum on fertilization and pregnancy rates (PRs) in assisted reproductive technology (ART) cycles.

DESIGN

Retrospective case control study.

SETTING

Assisted reproductive technology program at North Shore University Hospital.

PATIENTS, PARTICIPANTS

All patients undergoing an ART cycle in 1990 whose husbands did not have significant antisperm antibodies in the semen. Thirty-four female patients had significant antisperm antibodies level in the serum (antisperm antibodies-significant); 62 patients with no antibodies or nonsignificant levels constituted the control group (antisperm antibodies-negative). Incubation media were prepared with maternal serum in 37 of the antisperm antibodies-negative and in 10 of the antisperm antibodies-positive patients, whereas donor's serum (DS) was used for 25 and 24 patients, respectively.

MAIN OUTCOME MEASURES

Fertilization rate and clinical PR, defined as an intrauterine sac by transvaginal ultrasonography, were recorded for each group.

RESULTS

Analysis of variance showed a significant interaction between antisperm antibodies grouping and the type of media used, with fertilization rate in antisperm antibodies-significant patients significantly higher with maternal serum than with DS, whereas fertilization rate in antisperm antibodies-negative was quantitatively, though not statistically lower with maternal serum than with DS. When maternal serum was used, fertilization was higher in antisperm antibodies-significant than antisperm antibodies-negative. Of 29 clinical pregnancies, 11 were in antisperm antibodies-significant and 18 in antisperm antibodies-negative. In 10 of the pregnancies, maternal serum was used, whereas in 19 pregnancies DS was used. No variable was significantly predictive of pregnancy in the logistic regression analysis.

CONCLUSIONS

[1] Female patients with significant levels of antisperm antibodies in the serum had similar fertilization rates as patients with nonsignificant levels if DS was used. [2] The use of maternal serum in antisperm antibodies-significant patients did not result in inferior fertilization rates or the occurrence of pregnancy. [3] These findings suggest that a female antisperm antibodies may not hinder fertilization in vitro. [4] This study questions the value of routine screening of female serum for antisperm antibodies in ART.

The role of complement component C3b and its receptors in sperm-oocyte interaction

Previous studies have shown that human sperm that have undergone the acrosome reaction express a unique tissue-specific variant of the complement component 3 (C3)-binding molecule membrane cofactor protein (MCP, CD46) and that damaged or dead sperm activate the alternative pathway of complement and bind C3 catabolites. In this study we provide evidence that MCP on sperm that have undergone the acrosome reaction specifically binds dimeric C3b and that human sperm acrosomal proteases released during the acrosome reaction directly cleave C3, facilitating its binding to MCP. Furthermore, human and hamster oocytes can activate the alternative pathway of complement and also bind human C3 fragments. Monoclonal antibodies specific for complement receptors type 1 (CD35) and type 3 (CD11b/CD18) bind to the human oocyte plasma membrane, indicating that specific complement-binding molecules may play a role in the attachment of C3 catabolites to oocytes. Subsaturating concentrations of dimeric C3b (0.01-1 microM) promoted penetration of hamster oocytes by human sperm, whereas saturating doses (> 10 microM) inhibited this process. In addition, antibodies to both MCP and C3 significantly inhibited penetration of hamster oocytes by human sperm. These data provide evidence that regulated gamete-induced generation of C3 fragments and the binding of these fragments by selectively expressed receptors on sperm and oocytes may be an initial step in gamete interaction, leading to membrane fusion and fertilization.

Membrane cofactor protein (MCP, CD46) in seminal plasma and on spermatozoa in normal and "sterile" subjects

A sperm protein of molecular mass 43 kDa (the spermatozoa membrane cofactor protein, smMCP) and a seminal plasma protein of 60 kDa (ssMCP) were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting with four monoclonal antibodies (mAb) against membrane cofactor protein (MCP, CD46). These proteins served as factor I cofactors for the cleavage of methylamine-treated C3 (C3ma), the activity of which was blocked by M75, an MCP cofactor-activity-blocking mAb. Thus, these semen proteins are antigenic and functional homologous of MCP. On SDS-PAGE analysis these MCP migrated as single-band proteins which differed from the two-band forms of MCP expressed on other cells. smMCP was N-glycosylated but not O-glycosylated, while ssMCP was O-glycosylated: after deglycosylation of these proteins bands were detected at 38-40 kDa and 43 kDa on SDS-PAGE, respectively. These semen MCP are therefore, structurally different from the conventional MCP. ssMCP in both normal and "sterile" subject groups was determined by sandwich enzyme-linked immunosorbent assay. Seminal plasma in the two groups contained 250-700 ng/ml ssMCP. The difference between the two groups was marginal, although samples from normal subjects tended to show higher concentrations of ssMCP than samples from "sterile" subjects. No molecular difference was observed with ssMCP and smMCP in the two groups by SDS-PAGE/immunoblotting analysis. Immunohistochemical analysis suggested that MCP was positive in glandular epithelial cells and the lumen of the prostate, and in most intra-lumen cells of the testis. Using antibody M177, solubilized prostate and testis were analyzed by immunoblotting and compared with other cell MCP. The major band of MCP in the testis, but not in the prostate, was of 60 kDa, which aligned with ssMCP. No band of testis or prostate MCP, however, aligned with smMCP. ssMCP may be produced in the testis, while the origin of smMCP remains unknown. We hypothesize that ssMCP is important in the survival of spermatozoa, protecting them against local secretion of immunoglobulin and complement in the female genital tract, and that smMCP, which is expressed on acrosome-reacted spermatozoa, plays an essential role in the interaction of spermatozoa with oocytes.

Secretory monoclonal IgA antibody to human sperm produced by gastrointestinal immunization inhibits human sperm activity and mouse in vitro fertilization

BALB/c mice were immunized intragastrically with human sperm. Cells from the Peyer's patches and spleens of the immunized mice were for the preparation of hybridomas secreting antisperm monoclonal IgA (mcIgA). The specific ratio of IgA-secreting cells in Peyer's patches was much higher than that in spleen. The binding site on human sperm of 9 of 19 mcIgA was in the post-acrosomal region using an immunofluorescent assay. Two of eight selected mcIgA caused strong human sperm agglutination and three of them produced significant inhibition of mouse in vitro fertilization. No mcIgA tested caused obvious human sperm immobilization or inhibited mouse in vivo fertilization. In vitro assembly of selected mcIgA in ascites with mouse secretory component (SC) caused no significant changes in effects on sperm function and in vitro fertilization. By use of Western blotting, dimer or higher polymers were demonstrated in all selected mcIgAs and corresponding protein antigens in 6 of 8 selected mcIgAs. These results suggest that human sperm function may be inhibited and fertilization rate reduced by specific secretory IgA to human sperm and that secretory immunity to protein antigens of human sperm could be induced by intragastrointestinal immunization.

Characterization of a cDNA clone coding for human testis membrane cofactor protein (MCP, CD46)

Membrane cofactor protein (MCP) is a complement regulatory protein that acts as a cofactor for the cleavage of C3b and C4b by the serine protease factor I. We have previously reported the characterization of a functional MCP molecule on the acrosomal membrane. This protein migrated as a single band with a molecular weight of 40,000 Da, which is 10,000-20,000 Da smaller than the known MCP molecules, and is devoid of N- and O-linked sugars. We have proposed that the difference in molecular weight resulted from the lack of sugars. To investigate if this is due to the absence of glycosylation sites, we have characterized a cDNA clone from a human testis cDNA library. This cDNA corresponds to a peculiar MCP form previously described, which is characterized by the presence of the serine/threonine/proline-rich exon C (STPC) and the cytoplasmic tail known as CYT2, and we conclude that the absence of mature oligosaccharide of the sperm MCP cannot be totally attributed to a defect of N- and O-glycosylation sequences but rather reflects an alteration of the mechanisms of glycosylation in spermatozoa. The presence of functional MCP on the acrosomal membrane, as well as the other complement regulatory protein, decay-accelerating factor, strongly suggests that these proteins may act concomitantly to protect the acrosome-reacted spermatozoa from the attack of the complement present in the female genital tract.

Antisperm antibodies in women: variability in antibody levels in serum, mucus, and peritoneal fluid

OBJECTIVE

To look for patterns of antisperm antibody expression in women by exploring the levels of antisperm antibodies in different body fluids. This was achieved by studying sequential serum samples from individual patients and by comparing the levels of antisperm antibodies in serum from a number of patients with the levels of antisperm antibodies in cervical mucus or peritoneal fluid (PF).

DESIGN

Prospective studies were performed on sequential serum samples within a menstrual cycle. Retrospective studies were done to compare antisperm antibodies in serum and mucus or PF. The immunobead assay was used to measure antisperm antibodies in these fluids.

SETTING

Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire.

PATIENTS

A random sample of patients undergoing evaluation for infertility.

RESULTS

The levels of antisperm antibodies in sera drawn from patients at different points in a menstrual cycle stimulated by the presence of exogenous hormones did not change during the follicular phase of the menstrual cycle. Also, in many samples, the antisperm antibody level in serum did not correlate with the antisperm antibody levels in mucus or PF.

CONCLUSIONS

The data suggest that measurement of antisperm antibodies at a single point in time or from a single fluid is not sufficient when evaluating a woman for immunological infertility. The data also suggest that numerous and complex factors contribute to the expression of antisperm antibodies in women.

The effect of female antisperm antibodies on in vitro fertilization, early embryonic development, and pregnancy outcome

STUDY OBJECTIVE

To evaluate the extent to which human in vitro fertilization-embryo transfer (IVF-ET) alleviates immunological infertility.

DESIGN

Retrospective.

SETTING

In vitro fertilization program.

PATIENTS

Thirty-three patients with positive antisperm antibodies undergoing 50 cycles of IVF-ET in which maternal serum was replaced by 5 mg/mL of bovine serum albumin (BSA) comprised the study group. Seventy-one patients with tubal infertility served as controls. In 50 of these, medium was supplemented with 7.5% maternal serum, and 21 were assigned to BSA substitution.

RESULTS

Percentage of fertilization in the study group was significantly lower (41 +/- 31; mean +/- SD) than that of controls with maternal serum (77 +/- 15) and BSA (76 +/- 22). Early embryonic quality, as assessed by percentage of cleavage and morphological grading, was found to be inferior in patients with antisperm antibodies. The percentage of advanced embryos (greater than or equal to 4 blastomeres) at the time of transfer was 42 +/- 39 in the study group, compared with 65 +/- 23 and 75 +/- 35 for maternal serum and BSA controls, respectively. Percentage of morphologically favorable embryos (grades 1 and 2 in a 1 to 5 grading system) was 49 +/- 31 in the study group, compared with 78 +/- 35 and 74 +/- 23 for the controls. Percentage of clinical pregnancy was somewhat lower in the study group (12.5%) than in controls with either maternal serum (18%) or BSA (19%).

CONCLUSIONS

Antisperm antibodies may have an adverse effect on fertilization and early embryonic development. Female immunological infertility may not be completely alleviated by IVF-ET.

Correlation between quantitative antibody titers of sperm immobilizing antibodies and pregnancy rates by treatments

Immunological infertility in women who possessed sperm immobilizing (SI) antibodies made it very difficult to conceive using the usual treatments. We examined SI antibodies by the quantitative Sperm Immobilization Test and found the antibody titers (50% sperm immobilization unit: SI50 unit) associated with pregnancy rates. Patients with high SI50 titers (greater than 10 units) did not conceive by ordinary or repeated artificial inseminations with husband's semen (AIH) except when treated with in vitro fertilization (IVF) and embryo replacement. Patients with relatively low SI50 titers (less than 10 units) could conceive either by repeated or ordinary AIH, though the success rates were lower than by IVF-embryo replacement. It is important to assess the SI50 titers by the quantitative method to select treatments for infertile women with SI antibodies. In follow-up studies of the patients who conceived successfully, it was found that SI50 titers tended to decline as pregnancy proceeded.

Relationship of antibodies to sperm head to etiology of infertility in patients undergoing in vitro fertilization/embryo transfer

Antibodies to sperm head (ASA-H) are believed to impair reproduction, probably because of a reduction in fertilization of human oocytes. However, the incidence of ASA-H in couples with different etiologies of infertility undergoing in vitro fertilization/embryo transfer (IVF/ET) is unestablished. To examine this question, the semen, serum, and follicular fluid of 11 couples with unexplained infertility and 25 couples with tubal infertility undergoing IVF/ET were tested with the immunobead binding assay to identify ASA-H of IgA, IgG, and IgM isotypes. Comparing couples with unexplained vs. tubal infertility, 46% vs. 4% had ASA-H of at least one isotype in female serum (P = .006), 36% vs. 4% had ASA-H in follicular fluid (P = .023), 27% vs. 0% had ASA-H in semen (P = .023), and 18% vs. 4% had ASA-H in male serum (P = .022), respectively. ASA-H were present in one or more fluids tested in 55% of patients with unexplained infertility, compared to 8% of patients with tubal infertility (P = .005). Of the six women with ASA-H in their serum, 83% (5/6) were undergoing IVF/ET for unexplained infertility compared to 17% (1/6: P = .08) undergoing IVF/ET for tubal infertility. In summary, clinically significant ASA-H are present in a substantial number of infertile women undergoing IVF/ET, particularly those whose infertility is unexplained. Based on these findings, we conclude that it is efficacious to screen all women with unexplained infertility undergoing IVF/ET for ASA-H.

Results of in vitro fertilization in women with antisperm antibodies in serum, cervical mucus, and follicular fluid

This study was undertaken to investigate the presence of antisperm antibodies (ASA) in serum, cervical mucus, and follicular fluid (FF) of women undergoing in vitro fertilization and embryo transfer (IVF-ET). IgG and IgA ASA directed mostly against sperm head were found at similar concentrations in serum, cervical mucus, and FF of 2 of 34 patients. Ninety-one percent fertilization and 100% cleavage rates, respectively, were observed in one of the two patients. No fertilization occurred in the second patient. In both women, in vitro sperm penetration tests revealed hostile mucus and repeated postcoital tests were poor. It is concluded that the sperm-cervical mucus penetration test and mucus ASA measurements are useful in establishing the diagnosis of immunological infertility.

Sperm antibodies and human in vitro fertilization

In order to directly evaluate the effects of sperm antibodies in human in vitro fertilization (IVF), the authors preincubated donor sperm in female sera containing sperm antibodies and then inseminated supernumerary human oocytes from a gamete intrafallopian transfer (GIFT) program. The sperm were incubated for 30 minutes in medium containing 20% serum with antisperm activity (Test); or no antisperm activity (Control) as assessed by the immunobead test (IBT). Each oocyte was inseminated with 1 to 2 X 10(5)/ml of the preincubated motile sperm with Control or Test treatments allocated on a random basis. Six positive sera were tested in 17 experiments, resulting in a fertilization rate of 41% (25/61) versus 84% (36/43) for controls (P less than 0.001). When considered individually, three of six positive sera caused significant inhibition. The only serum that gave complete inhibition had the highest titer for IgG (10,000) and lower IgA (100). Absorption with protein A reduced the IgG titer to less than 10 and removed the fertilization inhibitory activity. These results confirm that sperm antibodies from female sera can inhibit human IVF.

Sperm antibodies and human fertilization

Previous investigations using zona-free hamster oocytes and salt-stored human zonae pellucidae, and retrospective analysis of routine human in vitro fertilization (IVF) results have suggested that sperm antibodies can impair the fertilizing capacity of human spermatozoa. The results of our investigations using viable human oocytes confirm that human antispermatozoal antibodies can inhibit fertilization by human spermatozoa. In the future we plan to examine the mechanism of fertilization inhibition, including characterization of the sperm antigens involved. These studies may facilitate the development of immunocontraceptive vaccines and of new treatments for immunological infertility.

Evaluation of immunobead test (IBT), tray-agglutination test (TAT), and sperm immobilization test (SIT)

The present investigation relates the results obtained by the indirect immunobead test (IBT) to those found during the tray-agglutination test (TAT) and sperm immobilization test (SIT) performed on 16 positive blood sera samples. An IB binding of greater than 50% can be regarded as significantly positive (p less than 0.05), since 77% of the positive IB samples with an IB binding of greater than 50% also revealed a TAT titer of greater than 1:8. The IBT is an excellent test for the detection of sperm antibodies during routine screening procedures.

Prevalence of sperm surface antibodies in the male partners of infertile couples as determined by immunobead screening

A single simple laboratory test for the detection of sperm surface antibodies is described. Spermatozoa from 300 men who were investigated for infertility were tested for sperm surface antibodies using the Immunobead test (IBT). IBTs for IgG, IgA, and IgM were performed on each sample as well as an IBT using an Immunobead with activity against both light and heavy immunoglobulin chains and therefore capable of detecting any of the three isotypes ("GAM-IBT"). An excellent correspondence was found between GAM-IBT-positive samples and those positive by one or more of the isotype-specific Immunobeads. In 29 of 32 positive tests, the GAM bead binding was within 5% of the most positive isotype-specific bead's binding. There were no false-positive or false-negative tests comparing the GAM-IBT with the isotype-specific IBTs.

Effect of sperm antibodies in females on human in vitro fertilization

The effect of sperm antibodies derived from the female partner's serum on fertilization and embryo cleavage was evaluated by analyzing the Royal Women's Hospital in vitro fertilization (IVF) data. The results suggest that antispermatozoal isoantibodies detected by the immunobead test (IBT) can interfere with IVF. Thus, in a group of patients with IBT-IgG and IBT-IgA sperm antibody titers of greater than or equal to 10 in serum, a low fertilization rate (15%) was obtained when the wife's serum was used as serum supplement in the IVF culture medium. Where replacement (antibody-negative donor or cord) serum was used in the culture medium, a higher fertilization rate (69%) was obtained (P less than 0.01). These results underline the importance of using replacement serum in cases where the wife has significant sperm antibody levels in her serum. Six pregnancies were obtained in the antibody-positive group (n = 20), five of which occurred in patients with IBT-IgG and IBT-IgA-titers less than 10, for a pregnancy rate of 5/9 in this subgroup. Four of these patients delivered (4/9). Analysis of larger groups of antibody-positive patients is required for further evaluation of these results and ascertainment of the likelihood of occurrence of posttransfer effects of sperm antibodies on the embryo.

Induction of the shaking phenomenon by IgA class antispermatozoal antibodies from serum

Serum was obtained from a woman with a high (greater than 1000) titre of antispermatozoal antibody of IgA immunoglobulin class determined by the indirect immunobead test (IBT). It was found that the serum could sensitize normal sperm to give a strong shaking reaction in the semen-cervical mucus contact test (SCMCT). The capacity to induce shaking was retained after absorption of the serum with protein A-sepharose, but lost after absorption with rabbit antihuman IgA. The results therefore suggest that antispermatozoal antibodies of IgA class from serum can induce shaking, and are consistent with the possibility that the Fc fragment (rather than secretory component or J-chain) may be important for induction of shaking in the conventional SCMCT.

In vitro fertilization results for women with sperm antibodies in plasma and follicular fluid

In vitro fertilization (IVF) and embryo transfer results were analyzed for three women with sperm antibodies in their plasma and follicular fluid. These preliminary results suggest that substitution of the patients' serum by replacement serum in the fertilization and embryo growth media may prove to be an effective means of improving IVF treatment for women with sperm immunity.

The immunoglobulin class of antispermatozoal antibodies in serum

The aim of this study was to determine the immunoglobulin class of circulating antisperm antibody using a technique called the indirect immunobead test (IBT). In the IBT sperm bound antibodies are detected using polyacrylamide beads coated with rabbit antihuman immunoglobulin classes IgG, IgA, and IgM. Of the 20 infertile men with serum immobilizins, 100% were found to be positive for sperm-bound IgG, 50% positive for IgA, and 0% positive for IgM, using the IBT. Similarly, 20 infertile females with serum immobilizins showed 95% positivity for IgG, 60% for IgA, and 15% for IgM. Thus there was a good correspondence between the presence of serum immobilizins as determined by the sperm immobilization test (SIT) and the IBT. This study provides data that indicates that IgG and IgA are the two major immunoglobulin classes of sperm antibody in male and female immune sera as detected by a simple, sensitive immunological technique, the serum IBT.

Detection of sperm antibodies in semen using the immunobead test: a survey of 813 consecutive patients

The aims of this investigation were to determine the incidence of sperm-bound antibodies in an unselected infertile population and also to further evaluate the immunobead test (IBT) with respect to specificity and reproducibility. The results of the survey showed that 7.8% of 813 men had antibodies of IgG and/or IgA class bound to the surface of at least 20% of their motile spermatozoa. The results of crossed-inhibition tests with purified human immunoglobulins and comparison of the IBT results with the sperm-immobilization test (SIT) in serum and sperm agglutination in semen suggested that the IBT is an immunologically specific test for sperm antibodies. Comparison of repeat tests on 123 patients showed that the IBT is reproducible in 97.5% of cases. There was no difference in mean count, percentage motile, or morphology between the groups of patients with positive or negative IBT results. The incidence of sperm agglutination was significantly (Chi-squared, p less than 0.001) higher in the positive IBT group. The results of this investigation therefore suggest that the IBT is an excellent test for routine screening of men for sperm antibodies.