Identification of antisperm antibodies on sperm of infertile men

Antispermatozoal antibody values after varicocelectomy

Although there are many causes of the production of antispermatozoal antibodies, there are still unknown aetiological factors. Antispermatozoal antibodies were investigated in the postoperative period in 25 infertile men with varicocele whose antispermatozoal antibody tests were negative in the preoperative period. Antispermatozoal antibodies were found in the serum in 4 of the 25 (16%) infertile men after varicocele operation. Postoperative genital infections were detected in 6 patients and antispermatozoal antibodies were present in only 2 of them. The correlation between these antibodies and varicocele has been demonstrated but there is no report on the association of antibodies with varicocelectomy in the literature to date.

Complement in human reproduction: activation and control

The behaviour of the complement system during human reproduction is now the focus of much scientific attention. The presence of antisperm antibodies in the reproductive tracts of some infertile individuals, and of complement in cervical and ovarian follicular fluid, suggests that complement-mediated damage of spermatozoa is involved in some cases of infertility. Further, deposition of maternal IgG and of complement in the extrafetal tissues indicates that complement activation occurs within the fetoplacental unit. Recently, three complement-regulatory proteins--decay-accelerating factor, membrane cofactor protein and CD59--have been detected on spermatozoa and in the extrafetal tissues. It is likely that these inhibitors are essential for normal reproductive function. This article reviews current understanding of the interaction of the complement system with cells and tissues involved in reproduction, with emphasis on the nature and function of the controlling proteins.

Physiologic relevance of the membrane attack complex inhibitory protein CD59 in human seminal plasma: CD59 is present on extracellular organelles (prostasomes), binds cell membranes, and inhibits complement-mediated lysis

We demonstrate here that CD59, an inhibitor of the membrane attack complex (MAC) of the complement system, is present in cell-free seminal plasma (SP) at a concentration of at least 20 micrograms/ml. Analyses by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and Edman degradation indicated that this protein, SP CD59, was similar, if not identical, to CD59 isolated from erythrocyte (E) membranes (E CD59). Like purified E CD59, SP CD59 also possesses a glycosyl phosphatidyl inositol (GPI) anchor and incorporates into the membranes of heterologous cells where it inhibits lysis by the human MAC. This phenomenon could be demonstrated not only if cells were incubated with purified SP CD59 but also if unfractionated SP were used. Further, CD59 in unfractionated SP bound to washed spermatozoa, increasing their membrane content of the protein. The mechanism by which this protein retains its GPI anchor while apparently present in the fluid phase is of interest and was further investigated. Using the techniques of high-speed centrifugation, fast performance liquid chromatography fractionation, and electron microscopy, we found that all detectable SP CD59 was associated with vesicular extracellular organelles. These organelles, named "prostasomes," were previously known to be present in SP and to interact with spermatozoa, although their function was uncertain. Interaction of heterologous E with prostasomes rendered the cells more resistant to lysis by human MACs. We propose that these organelles represent a pool of CD59 from which protein lost from spermatozoa, perhaps as a result of low level complement attack or of normal membrane turnover, can be replenished.

Comparison of the indirect immunobead, radiolabeled, and immunofluorescence assays for immunoglobulin G serum antibodies to human sperm

The relative sensitivities of the indirect immunobead test, the indirect flo cytometric immunofluorescence assay, and an indirect radiolabeled antiglobulin assay were compared. Eighteen immunobead test positive sera and 18 negative sera were used as the standard for the other two assays. Of the 18 positive sera, 14 (77%) and 5 (27%) were positive in the immunofluorescence assay and the radiolabeled antiglobulin assay, respectively. Four (22%) of the low titer immunobead test positive sera were negative by both the immunofluorescence assay and the radiolabeled antiglobulin assay. However, there was a significant positive correlation between the results of the immunofluorescence assay and the radiolabeled antiglobulin assay (r = 0.73) and between the results of the radiolabeled antiglobulin assay and the titer of the immunobead test (r = 0.82). The use of an unselected sperm population in the radiolabeled antiglobulin assay and the classical indirect immunofluorescence method using methanol-fixed sperm gave false-positive results in the radiolabeled antiglobulin assay and the immunofluorescence assay. These results suggested that immunoglobulin G antisperm antibody positive sera may be reactive both to sperm surface and internalized sperm antigens.

Radio-immuno binding test for anti-sperm antibody detection: analysis and critical revision of various methodological steps

The authors report the results of a methodological study to optimize a radioimmunoassay to detect anti-sperm antibodies. They describe here the definitive methodology with all the data relating to the laboratory trials conducted at each step of the technique. Results seem to demonstrate that this radioimmunological method is sufficiently simple, specific, sensitive and reliable for use in a highly specialized laboratory of reproductive immunology. Furthermore, this type of analytical approach, whilst indicating once more the difficulty of the technical study of anti-sperm autoimmunity, confirms (with concrete data) the necessity of being extremely "prudent" in evaluating the results of this kind of anti-sperm antibody test.

A reverse (antibody capture) enzyme-linked immunosorbent assay for detection of antisperm antibodies in sera and genital tract secretions

A reverse (antibody capture) enzyme-linked immunosorbent assay (ELISA) for detection of antisperm antibodies has been developed. The assay enables detection of immunoglobulin (Ig) M, IgG, IgA, or IgM, IgG, and IgA--antisperm antibodies in serum, cervical mucus, and seminal plasma samples. The reverse ELISA is more specific and sensitive than conventional ELISA in detecting human antisperm antibodies of different isotypes. Using this assay, statistically significant differences in levels of antibodies between infertile and fertile individuals were demonstrated in sera and in genital tract secretions. Studies with 143 infertile couples revealed that the presence of antibodies in sera was not necessarily reflected in individual's genital tract secretion and vice versa. These data emphasize the importance of detecting antisperm antibodies in sera as well as in genital tract secretions for correct evaluation of sperm immunity.

Lack of complement activation in the seminal plasma of men with antisperm antibodies associated in vivo on their sperm

A specific and sensitive "sandwich"-type radiolabeled antiglobulin assay (RAA) using monoclonal anti-human C5b-9 neoantigen and polyclonal anti-human C5b-9 was used to evaluate the presence of the in vivo product of human complement (C) activation (SC5b-9) in the seminal plasma (SP) of 19 fertile and 61 infertile men. SP SC5b-9 was detectable in 7 (8.7%; 1 fertile and 6 infertile men) of the 80 men with a range of 10 to 175 ng/ml. Levels of SP SC5b-9 in other men were below the limit of detection (less than 10 ng/ml). Of the 33 infertile men with sperm-associated immunoglobulin (Ig) G and/or IgA, 27 (82%) had undetectable levels of SP SC5b-9 immunoreactivity. There was no correlation between the SP SC5b-9 levels and the degree of sperm-associated IgG (r = 0.086) or IgA (r = 0.23) activity. However, significant deposition of sperm-bound C5b-9 due to autologous C activation was demonstrated by flow cytometry of donor sperm treated with sera from autoimmune men with ASA in their sera and on their sperm. These findings suggest that sperm-bound Ig cannot activate C in SP.

Assessment by fluorescence-activated cell sorting of whether sperm-associated immunoglobulin (Ig)G and IgA occur on the same sperm population

Two-color fluorescence-activated cell sorting of antisperm antibody-positive sperm was used to detect simultaneously the presence of immunoglobulin (Ig)A and IgG antisperm antibodies associated in vivo on a man's sperm. Sperm positive for sperm-associated Ig were analyzed using phycoerythrin-conjugated antihuman IgA and fluorescein isothiocyanate-conjugated antihuman IgG; up to 87% of the same spermatozoa were stained with both labels. Sperm positive for only one of the antisperm antibody isotypes stained up to 90% of a man's sperm with only one fluorochrome. Immunocytochemistry studies revealed similar patterns of sperm binding for sperm-associated IgG and IgA. These results suggest that the sperm antigenic determinants reacting with antisperm IgA and IgG are present on the same sperm population at similar locations on the sperm surface.

Comparison of the direct radiolabeled antiglobulin assay and the direct immunobead binding test for detection of sperm-associated antibodies

Thirty-seven semen samples were assayed for sperm-associated IgG and IgA using the immunobead test. Portions of these sperm samples were sent for testing with a direct radiolabeled antiglobulin assay and the testing results were compared. If the results of the immunobead test when only tail-tip bead binding was noted are regarded as negative, there was close correlation between the two assay methodologies.

A radiolabeled antiglobulin assay to identify human cervical mucus immunoglobulin (Ig) A and IgG antisperm antibodies

Antisperm immunoglobulin (Ig) A and IgG antibodies in human cervical mucus (CM) were identified by a radiolabeled antiglobulin assay. Cervical mucus samples from fertile and infertile women were exposed to a 1:3,200 dilution of 2-mercaptoethanol (2-ME), and 5 micrograms of the solubilized CM protein were assayed for the presence of IgA and IgG antisperm and anti-Candida activity by the radiolabeled antiglobulin assay. Purified human secretory IgA and IgG exposed to 2-ME retained the molecular integrity and functional activity of the untreated antibody molecules. CM aliquots collected after high-performance liquid chromatography (HPLC) fractionation were assessed for antisperm antibody activity; antisperm antibody activity was retained in the appropriate IgA or IgG CM fractions. The incidence of CM antisperm antibodies was minimally affected when the radiolabeled antiglobulin assay was performed with a motile sperm population. Approximately 70% of the CM IgA antisperm antibodies were of the IgA1 subclass; CM IgG was primarily of the IgG4 subclass. When Candida antigen was substituted for sperm in the radiolabeled antiglobulin assay, the CM antisperm antibodies were found to be exclusively sperm-specific. These data indicate that the radiolabeled antiglobulin assay using 2-ME to extract CM antibodies is a specific method for the assay of antisperm antibodies in CM.

Quantitation of immunoglobulin G on human sperm

An indirect inhibition assay was devised to quantitate the amount of immunoglobulin molecules on the surface of human sperm. Sperm-associated IgG was used to inhibit competitively 125I-labeled polyclonal anti-human IgG from binding to human IgG affixed to microtissue culture plate wells. Standard curves for the assay were derived by substituting soluble IgG in the supernatant of the tissue culture wells for sperm-associated IgG. The intraassay coefficient of variation was 6.7%; the interassay coefficient of variation was 5.6-21% depending upon the IgG antisperm antibody-positive plasma sample assayed. The assay technique was highly correlated (r = 0.99) with the number of antibody-bound sperm added to the supernatant. When different sperm donors were utilized as an antigen source, the coefficient of variation was 15.6% for positive plasmas and 19.3% for negative plasmas. The indirect inhibition assay showed a strong correlation (r = 0.91) with a previously described radiolabeled antiglobulin assay for sperm-associated IgG.

Detection of antisperm antibodies on the surface of motile spermatozoa. Comparison of the immunobead binding technique (IBT) and the mixed antiglobulin reaction (MAR)

Investigators testing for antisperm antibodies have recently focused on tests that detect the Ig classes of the sperm-bound antibodies. The aim of this study was to compare the sensitivity of two of these tests, viz. the immunobead binding technique (IBT) and the mixed antiglobulin reaction (MAR). Twenty-one male or female sera were tested for IgG and IgA antisperm antibodies with the IBT and the MAR. The sera were selected on the basis of the IBT results, and the MAR was carried out without knowledge of these results. For IgG antisperm antibodies, there was a highly significant correlation between the two tests (P = 0.0043), whereas, for IgA antisperm antibodies, the correlation was poor (P = 0.2951), because the IBT revealed a positive reaction for IgA in sera in which no such antibodies could be detected by the MAR.

A direct immunofluorescence test for the detection of sperm surface bound antibodies. Comparison with sperm agglutination test, indirect IF test and MAR test

A direct immunofluorescence (DIF) test using sperm suspensions and F (ab')2 antisera was carried out on 30 patients with sperm-agglutinating (SA) activity and on 25 negative controls. Its results were related with the occurrence of SA activity in serum and seminal plasma, with the results of the indirect IF test and those of the direct IgG-MAR test. DIF test gave positive results in all patients with significant serum SA activity, even when it was undetectable in seminal plasma, except in 2 cases with serum IF-reactivity for IgM, and negative results in all controls. IgG were involved in IF-reactivity in 88.4% of positive cases and IgA in 42.3%. IgA were always found in association with sustained SA activity in seminal plasma. In these cases the IgG-MAR test might not result strongly positive, in spite of the high titre of SA activity in semen.

The relationship of circulating antisperm antibodies to sperm surface antibodies in infertile men

The correlation between the amount and location of antisperm antibody binding to the sperm surface and the level measured in the serum has not been previously reported. Hence, the value and limitations of screening blood sera from men with suspected immunologic infertility are not currently known. In this study 70 paired sera and semen samples were assayed by the immunobead test (IBT). A screening protocol for blood sera was constructed to be 100% sensitive for detecting semen specimens with 20% or more of sperm binding IgG or IgA immunobeads. The specificity of this screening protocol was determined to be 79%. Serum IgA was not a good predictor of IgA on the sperm surface. The true positive predictive rate for antisperm antibodies on the sperm surface using circulating antisperm antibodies as a screening assay was estimated to be as low as 35%. There was little correlation between the site of immunobead binding following passive antibody transfer from patients' sera to donor sperm and the site of naturally occurring antibodies on the patients' sperm surface. Although direct assessment of antibodies on the sperm surface is preferred, these data suggest that serum IgG alone can be used as a sensitive screening assay for antisperm antibodies in men. A positive screen dictates that a direct assay on semen should be performed.

Effect of repeated washing on sperm-bound immunoglobulin G

The effect of sperm washing on the stability of sperm-bound immunoglobulin G (IgG) antibody derived from plasma from four patients and also IgG bound in vivo on the spermatozoa of four other men was quantitatively evaluated. In the first series of experiments, human spermatozoa were incubated with an IgG antibody-containing plasma and subjected to 18 cycles of sperm washing. In the second set of experiments, spermatozoa from men positive for sperm-bound IgG were subjected to four cycles of sperm washing. The amount of residual antibody bound to a constant number of spermatozoa was quantitated by a radiolabeled antiglobulin assay during and following the washing procedures. There was no significant loss of sperm-bound antibody due to the washing procedures. The results of these studies undermine the utility of sperm washing as an effective treatment of antibody-mediated infertility in men.

Indirect mixed antiglobulin reaction (MAR) as a screening procedure for antisperm antibodies. II. Clinical studies

In this study the question was raised whether the indirect mixed antiglobulin reaction (MAR) using donor spermatozoa could substitute the direct MAR requiring motile spermatozoa in the patient's ejaculate in the screening for antisperm antibodies. Serum and seminal plasma from 48 men selected on the basis of the results in the direct MAR were tested by the indirect MAR. Both tests were carried out for IgG and IgA antisperm antibodies. A statistically significant correlation was found both between the sperm-bound IgG and the free IgG antisperm antibodies in serum as well as in seminal plasma and between sperm-bound IgA and the free IgA antisperm antibodies in seminal plasma whereas no correlation was found between the sperm-bound IgA and the free IgA antisperm antibodies in serum. This finding strongly supports the concept that the major part of the IgA antisperm antibodies in the ejaculate are locally produced.

Quantitation of sperm bindable IgA and IgG in seminal fluid

Seminal fluid and serum from 95 infertile males were assayed for sperm bindable immunoglobulins using an indirect ELISA with whole target sperm. The ELISA method was compared to seminal fluid and serum immobilization and agglutination assays (functional assays). In this infertile group, the ELISA assay was positive in 22% of seminal fluids (greater than 1.2 fg IgA/sperm and greater than 0.3 fg IgG/sperm). The seminal fluid antibodies were IgA and had an accompanying elevated IgG component in 78% of patients. There was a 96% correlation between negative seminal fluid functional assays and negative ELISA, and a 95% correlation between positive seminal fluid functional assays and positive ELISA. Positive serum sperm antibody tests were found in 71% of the infertile males with positive seminal fluid sperm antibodies, but 29% of the infertile males with strongly positive IgA seminal fluid sperm antibodies showed normal levels of serum sperm antibodies by either ELISA or functional assays. The ELISA method gives reproducible quantitation of sperm antibodies in seminal fluid and correlates well with accepted functional assays. Comparisons with serum sperm antibody assays suggests that seminal fluid sperm antibody analysis complements the serum analysis of sperm antibodies.

Failure to identify HLA ABC and Dr antigens on human sperm

An indirect radiolabeled antiglobulin assay (IRAA), adsorption procedures, and an indirect immunofluorescent assay using cytofluorometry (IFAA) failed to identify HLA ABC or D/Dr antigens associated with untreated human sperm or human sperm exposed to capacitating conditions. Two monoclonal clones against HLA ABC and two clones against Dr antigens were utilized. Test results in the IRAA were not different regardless of whether sperm from fertile men or human red blood cells were employed in the IRAA. However, there were highly significant differences in the IRAA between the HLA antigen expression of human sperm and leukocytes. If the antihuman HLA monoclonal antibody was preadsorbed with 25 X 10(6) sperm, there was no diminution in the ability of the adsorbed antibody to identify HLA antigens on leukocytes; however, preadsorption with 2.5 X 10(6) leukocytes reduced the activity of the monoclonal antihuman HLA antibody to levels equivalent to background activity.

The clinical relevance of classes of immunoglobulins on spermatozoa from infertile and vasovasostomized males

Following reversal of vasectomy, conceptions occur even when antisperm antibodies are present in the seminal plasma, but this is most unusual in men with similar titers of such antibodies who are spontaneously infertile. To clarify the differences between antisperm antibodies occurring in infertile men and those associated with vasectomy reversal, we have studied 23 spontaneously infertile men and 22 men who underwent vasectomy reversal, all of whom had antisperm antibodies detected in seminal plasma by the same tray agglutination test. The class of antibody on spermatozoa was defined by a double-antibody technique using diluted rabbit anti-human IgG, IgM, or IgA or secretory component, followed, after washing, by 125I-labeled donkey anti-rabbit Ig. The results have shown that similar amounts of IgG and IgM were present on the spermatozoa, but infertile men had significantly more IgA and especially more secretory component than men who underwent vasectomy reversal. This was associated with significantly greater impairment of penetration of cervical mucus in the former group. It appears that the type of antibody on the spermatozoa may vary according to the stimulus for its production.

The effect of immunoglobulin occurring on human sperm in vivo on the human sperm/hamster ova penetration assay

We selected 91 infertile men who were tested for increased sperm-associated immunoglobulin and also tested in the human sperm/hamster ova penetration assay. There was a statistically significant association between the presence of increased sperm-associated IgG alone (p = 0.0218) and both sperm-associated IgG and A (p = 0.0187) when correlated with the failure to penetrate any hamster ova. There was a trend but no statistical significance when sperm-associated immunoglobulin A alone was present. There was a trend but no statistical relationship between the presence of sperm-associated immunoglobulin and the sperm penetration assay when the criteria for normality of the sperm penetration assay was a 15% or greater ovum penetration rate.

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.

Effect of male antisperm antibodies on sperm fertilizability in vitro

Male partners of 129 infertile couples were evaluated for antisperm factors by using the hamster zona-free ovum (HZFO) test. Sperm-agglutinating activity and antifertilization factors were assessed by adding the male partner's serum to donor sperm in the HZFO-serum antibody (HA) test. When patient's HZFO scores were less than 20% of the hamster ova fertilized, fertilization by patient's serum in the HA test. Of 13 samples that failed to fertilize any of the hamster ova, nine were antibody-negative, of which seven had at least one extremely deficient sperm parameter. Of the four men with positive serum, two had normal and one had abnormal semen (one did not have a complete semen analysis). These data emphasize the need to test male partners for a decline in fertilizing capacity, which is frequently related to the presence of serum antisperm factors. These tests could be used to identify paternal and maternal components (sperm and serum) that may hinder fertilization in fertilization programs.

Immunological screening of a male population with infertile marriages

Four hundred not preselected male partners of infertile marriages were screened for the presence of anti-sperm antibodies. Serum and seminal plasma specimens from each patient were tested by the modified slide agglutination test (MSAT) and by the sperm-immobilization test. In addition, the IgG MAR test was performed on fresh ejaculates. Thirteen per cent of patients showed sperm agglutinating activity in serum and 5.7% also in seminal plasma. Sperm-immobilizing activity was found in 4.7% of serum and 1% of seminal plasma specimens, always associated with a high titre of sperm agglutinating activity. A highly significant linear correlation was found between the results of the MAR test and serum sperm-agglutinating activity; the presence of sperm-agglutinating activity in seminal plasma was always associated with MAR test positivity greater than 50%. The incidence of anti-sperm antibodies was not significantly different in patients with normo-, oligo- and azoospermia. The effectiveness and the easiness of both the MAR test and the MSAT do not justify, in our opinion, the utilization of more complex and expensive techniques for the detection of anti-sperm antibodies.

Identification of antibody-laden sperm by cytofluorometry

A direct assay for measuring sperm-associated immunoglobulin G (IgG) and an indirect assay for measuring IgG plasma antisperm antibodies were devised utilizing fluorescein-labeled antihuman IgG and a fluorescein-activated flow cytometer. The method singularly analyzed Ig attached to the surface of sperm because sperm and nonsperm cells were separately assessed. The direct assay technique results correlated with results from a previously reported direct radiolabeled antiglobulin assay. As few as 100,000 sperm are required in the indirect method; the sensitivity of the indirect technique corresponded with that of a previously reported indirect radiolabeled antiglobulin assay.

Immunoglobulin in seminal fluid of fertile, infertile, vasectomy and vasectomy reversal patients

We measured the concentrations of IgG, IgA, and IgM, in the seminal fluid of 16 fertile men, 77 men of infertile marriages, 21 men who had undergone vasectomy reversal and 5 men who had undergone vasectomy only. The lower limits of sensitivity of the assay was 0.04 mg./dl. IgG (mean concentration 3.29 mg./dl., range 0.48 to 15.41 mg./dl.) and IgA (mean concentration 1.11 mg./dl., range 0.05 to 19.11 mg./dl.) were measureable in all specimens, but IgM (range 0.04 to 0.76 mg./dl.) was measureable in only 20 per cent. Intrasubject variability of IgG and IgA concentrations expressed as the coefficients of variation of serial determinations ranged from 18 to 40 per cent and 29 to 52 per cent, respectively. Discrepancies between the presence or absence of measurable IgM in serial determinations were unusual. The mean concentrations of seminal fluid IgG and IgA in the fertile group were not significantly different from the other patient groups. However, IgM was measurable in only 13 per cent of specimens from the fertile patients but in 62 per cent of specimens from the vasectomy reversal patients (p = 0.003). This suggests disruption of the blood-genital tract barrier following vasectomy and continuing after vasectomy reversal.