Immunoglobulin concentration in serum and seminal fluid from men with and without sperm-agglutinating antibodies

Dominant Prostasome Immunogens for Sperm-Agglutinating Autoantibodies of Infertile Men

The presence of naturally occurring anti-sperm antibodies (ASA) is a well-known cause of infertility in men and women, but the antigens for these antibodies are poorly characterized. We have previously shown that prostasomes adhere to sperm cells and that prostasomes are major targets for ASA associated with infertility. These autoantigens have not been characterized. We used 2-dimensional electrophoresis, immunoblotting, and mass-spectrometry to identify the prostasome antigens for these autoantibodies. By these techniques, we revealed that prolactin-inducible protein (PIP) and clusterin were dominant prostasome immunogens for sperm-agglutinating autoantibodies of 20 patients with immunological infertility. PIP was identified by 19 of 20 (95%) patient sera and clusterin by 17 of 20 (85%). In addition, 10 sporadically occurring prostasomal antigens were identified in this context, viz alcohol dehydrogenase [NADP+], annexin I, annexin III, BRCA1-associated ring domain protein 1, heat shock 27-kd protein, isocitrate dehydrogenase, lactoylglutathione lyase, NG,NG-dimethylarginine dimethylaminohydrolase 1, peroxiredoxin 2, and syntenin 1.

A novel tissue engineering-based assay for immunological infertility

Antisperm antibodies (ASA) are present in 9-36% of infertile couples, a condition called immunological infertility. The variability of ASA in terms of antigenic specificity and biological effects has made it difficult to design a test able to distinguish reliably between ASA that contribute to infertility and those that do not. To develop a reliable and reproducible method able to detect sperm antibodies, we took advantage of recent progress made in tissue engineering techniques. We used collagen gel as a bio-scaffold for the production of engineered sperm analogues. The advantages of using collagen gels include biocompatibility, ease of fabrication and low cost. We found that this tissue engineering-based assay is more specific and more sensitive than a conventional test routinely used for ASA detection. In addition, it exhibited low intra- and inter-variations. We envision the use of this novel approach for the detection of a variety of autoantibodies in autoimmune diseases. In addition to diagnostic purposes, tissue-engineering based tests could be useful in monitoring treatments with bio-drugs.

Human Male Genital Tract Secretions: Both Mucosal and Systemic Immune Compartments Contribute to the Humoral Immunity

In contrast to numerous studies of female genital tract secretions, the molecular properties of Abs and the magnitude of humoral responses in human male genital tract secretions to naturally occurring Ags and to mucosal and systemic immunizations have not been extensively investigated. Therefore, seminal plasma (SP) collected from healthy individuals was analyzed with respect to Ig levels, their isotypes, molecular forms of IgA, and for the presence of Abs to naturally occurring Ags, or induced by systemic or mucosal immunizations with viral and bacterial vaccines. The results indicated that in SP, IgG and not IgA, is the dominant Ig isotype, and that IgM is present at low levels. IgA is represented by secretory IgA, polymeric IgA, and monomeric IgA. In contrast to the female genital tract secretions in which IgA2 occurs in slight excess, the distribution of IgA subclasses in SP resembles that in plasma with a pronounced preponderance of IgA1. The IgG subclass profiles in SP are also similar to those in serum. Thus, SP is an external secretion that shares common features with both typical external secretions and plasma. Specifically, SP contains naturally occurring secretory IgA Abs to environmental Ags of microbial origin and to an orally administered bacterial vaccine, and plasma-derived IgG Abs to systemically injected vaccines. Therefore, both mucosal and systemic immunization with various types of Ags can induce humoral responses in SP. These findings should be considered in immunization strategies to induce humoral responses against sexually transmitted infections, including HIV-1.

Prostasome antigens as targets for sperm agglutinating antibodies demonstrated by 1-D gel electrophoresis and immunoblottings

Many immunoinfertile men have sperm agglutinating antibodies that are directed against prostasome-derived antigens, but these antigens have not been defined so far. We selected serum samples with high ELISA titres against prostasomes from a group of immunoinfertile patients with sperm agglutinating antibodies and used the sera for immunoblottings on 1-D SDS-PAGE of prostasomes and sperm cells. The immunoblottings with individual antiprostasome antisera on 1-D SDS-PAGE of prostasomes, revealed three to 10 bands for each serum. Eighty-five per cent of the serum samples contained bands in the 70-75 kDa region and 80% of the samples contained bands in the 50-55 kDa region. Immunoblottings of extracted sperm cells, revealed one to six bands in the molecular weight range 25-82 kDa and two of the samples recognized two bands with molecular weights (50 and 43 kDa) similar to immunoblottings of prostasomes. The prostasomal antigens recognized by the high titre-antisera of immunoinfertile men were generally different from the sperm antigens recognized by the same sera. This suggests that prostasomes offer a new set of antigens available for research on male immunoinfertility and immunocontraception.

A new test for immunological infertility: an ELISA based on prostasomes

Antisperm antibodies (ASA) are present in patients with immunological infertility, but the antigens are poorly characterized. Prostasomes adhere to sperm cells and are recognized as antigens for ASA. This investigation aimed to study the prevalence of antiprostasome antibodies in ASA-classified sera. We studied the reactivity of ASA-positive sera from 116 immunoinfertile patients. Ninety-seven per cent (113 of 116) of the patients' sera contained IgG antibodies against seminal prostasomes. Accordingly, prostasomes are one of the major targets for ASA. An enzyme-linked immunosorbent assay based on prostasomes is simpler to perform than ASA tests presently in use. It is also easier to achieve reproducible and standardized results.

Measurement of immunoglobulin G, A and M concentrations in boar seminal plasma

How the immune system relates to the boar reproductive tract is not well defined. This is an important area of study because disease-causing agents may be transmitted through boar semen. We have previously identified porcine reproductive and respiratory syndrome virus (PRRSV) in boar semen and wanted to identify PRRSV-specific antibodies within seminal plasma. However, literature documenting total immunoglobulin concentration or the predominant immunoglobulin isotype in boar semen was not available. Therefore, we developed a sandwich enzyme-linked immunoassay (ELISA) to quantitate total IgG, IgA and IgM in seminal plasma from 16 healthy, nonvaccinated, adult boars (n = 102 semen samples). In seminal plasma, IgG was the predominant isotype followed by IgA and IgM. Mean levels +/- the standard deviation followed by the 95% confidence interval of IgG, IgA and IgM were 23.2 +/- 14 microg/mL (15.5 to 31.0), 4.8 +/- 2.5 microg/mL (3.5 to 6.2) and 3.7 +/- 1.7 microg/mL (2.7 to 4.7), respectively. These concentrations of immunoglobulins in seminal plasma were considerably lower than in other swine secretions, which might allow for the survival of infectious agents in boar semen.

Mucosal immune system of the human genital tract

In contrast to the pronounced dominance of secretory IgA over other immunoglobulin isotypes in human saliva, tears, milk, and gastrointestinal fluids, secretions of both female and male genital tracts contain more IgG than secretory IgA. Both IgG and IgA are derived, to a variable degree, from the systemic immunoglobulin pool as well as from local synthesis. The origin of IgG- and IgA-plasma cell precursors destined for the genital tract is unknown, but indirect evidence suggests that mucosal inductive sites localized in the rectum, small intestine, and especially in the nasal cavity contribute such precursors to the female genital tract. Several studies indicated that intranasal immunization of various species, including humans, was efficient at inducing antigen-specific antibody responses in the female genital tract; however, whether this route is also effective in males has not been explored.

Detection of antisperm antibodies on the surface of living spermatozoa using flow cytometry: preliminary study

OBJECTIVE

To assess the use of flow cytometry (FCM) analysis of living spermatozoa subjected to indirect immunofluorescence staining with the mouse anti-human immunoglobulin (Ig)G monoclonal antibodies (FCM test) as an objective method for the detection of antisperm antibodies in semen and serum.

DESIGN

The comparative studies were conducted with the direct and indirect mixed antiglobulin reaction (MAR) and FCM test performed by FCM analyzer FACSCAN (Becton Dickinson Immunocytometry Systems, Mountain View, CA).

SETTING

Clinical infertile service.

PATIENTS

Seventy-six semen and 20 sera samples of infertile patients were analyzed.

RESULTS

For IgG in semen there was a highly significant correlation between the direct MAR and FCM test. Six of 12 IgG-positive samples revealed also IgA, and just one sample, which showed negative MAR, was positive for IgM in FCM test. Flow cytometry test and indirect MAR showed also a highly significant correlation of the results of IgG detection in sera.

CONCLUSIONS

Flow cytometry test may be used to verify that IgG antisperm antibodies are on the surface of living spermatozoa either retrieved directly from an ejaculate or after exposure to serum and to determine proportion of antisperm antibodies-positive spermatozoa, titer, and quantity of antibodies bound to the cell surface.

Methods to evaluate reproductive health of the human male

The proportion of men suffering from subfertility has increased and sperm quality of the general population has decreased rather dramatically during the last decades. Conventional methods to measure sperm concentration, motility, and morphology give a rough estimate of the fertilizing capacity of semen. Objective assessment of motility characteristics and morphometric image analysis may give more precise information, but technology still needs to be refined. Some aspects of the functional capacity of spermatozoa may be impaired before measurable changes occur in their number or morphology. A battery of tests is described to evaluate sperm migration and capacitation, acrosome reaction and acrosin activity, zona adhesion and binding, sperm oolemma fusion, sperm head decondensation, and chromatin make-up. Also methods are described to localize the possible site of impairment of the genital tract. Implementation of these methods may enhance our capability to detect minor effects of environmental hazards on male reproductive health.

Effect of different procedures of semen preparation on antibody-coated spermatozoa and immunological infertility

To assess whether procedures of semen preparation can reduce the proportion of antibody-coated spermatozoa, semen samples with positive direct mixed antiglobulin reaction (MAR) were washed in media supplemented with 10% or 50% fetal cord serum (FCS). Washing reduced the MAR to a negative level, but the MAR was identical to that in the native semen when spermatozoa were resuspended in serum-free medium. Donor spermatozoa, recovered after swim-up in media supplemented with 10% or 50% FCS or after passage through a column with 7.5% human serum albumin (HSA), were incubated in serum samples with both agglutinating and cytotoxic antisperm antibodies. Cytotoxic activity was significantly reduced against sperm filtered over the albumin column.

Determination of adenosine triphosphate in human semen to estimate the fertilizing potential and to quantify sperm antibodies

The measurement of the ATP content of fresh semen is as accurate as the estimation of sperm motility by conventional methods in discriminating between semen of fertile versus subfertile men. The ATP content of frozen thawed donor semen is correlated with the probability of conception per cycle of insemination. Exact quantification of cytotoxic sperm antibodies in serum is possible with the adenosine-triphosphate-release-cytotoxicity test, since measurement is free of the bias of microscopic examination. The procedure has been simplified by testing only one serum dilution and calculating the 'sperm toxicity index'.

The indirect mixed antiglobulin reaction test using a commercially available kit for the detection of antisperm antibodies in serum

A simple procedure is described for the detection of antisperm antibodies of the IgG class in human serum using the indirect mixed antiglobulin reaction (MAR) test. The test uses only one dilution of serum (1/16) and no washing procedures. The test was performed in 361 sera. Comparative studies were conducted with the tray agglutination test (TAT) in 164 sera and with the direct MAR test on semen in 110 cases. In 24 sera with borderline test results, and in 13 sera with discordant findings, evidence of antisperm antibody activity was investigated by means of additional testing, namely, the adenosine triphosphate release cytotoxicity test (ARCT) and the indirect immunobead tests (IB) for IgA and IgM. Using the value of 40% reaction between motile spermatozoa and coated latex particles as the lower limit of significant activity, the indirect SpermMAR test has a sensitivity of 96% and specificity of 87%. The two false-negative indirect MAR results occurred in cases with IgM, the clinical significance of which is doubtful. Hence, the indirect MAR test appears to be an ideal screening procedure for sperm antibodies in serum since it is easy to perform and sensitive. Considering the false-positive rate of 13%, additional tests should, however, be performed on sera with a reaction of 40% or more in order to assess the relevance of the antibodies as a cause of infertility.

Evaluation of the direct and indirect mixed antiglobulin reaction with latex particles for the diagnosis of immunological infertility

The direct Mixed Antiglobulin Reaction (MAR test) is a simple method for the detection of auto-antibodies attached to spermatozoa in fresh semen. The test was improved by using IgG-coated latex particles (SpermMAR) instead of coated red blood cells. A positive direct MAR test with adherence of latex particles to 40% or more of the motile spermatozoa was found in 16 out of 312 men (5%) consulting for infertility, but never in fertile controls. The percentage of motile spermatozoa reacting with the coated latex particles was correlated significantly with the serum titre of sperm agglutinins assessed by the tray agglutination test. The direct MAR test on semen was highly specific but rather insensitive, particularly if the serum titre of agglutinins was low. The same kit (SpermMAR) can be used to detect circulating sperm antibodies in serum of male or female patients with the indirect mixed antiglobulin reaction. The indirect MAR test discriminated clearly between serum with low (less than 1/32) or high (greater than 1/32) titres of circulating agglutinins assessed by the tray agglutination test. Considering their simplicity and accuracy, both the direct test on semen and the indirect spermMAR test on serum should be included in the routine evaluation of the infertile couple.

Seminal plasma immunoglobulins of the Indian buffalo

Seminal plasma immunoglobulins of normospermic fertile Indian buffalo bulls were investigated using rabbit antibuffalo immunoglobulin (polyvalent) serum, rabbit antibuffalo IgG and IgM serums, gel diffusion, and immunoelectrophoretic analysis. Immunoglobulin G was the predominant immunoglobulin in the seminal plasma of the buffalo. Strong antigenic cross reactions were observed between the seminal plasma IgG molecules of the buffalo and cattle, indicating the structural homology of seminal plasma IgG of these two species. These observations are in accordance with the close taxonomic and phylogenetic relationship between buffalo and cattle in the evolution of ruminant species.

Modification of the slide agglutination test for the detection of sperm-agglutinins

We have modified the slide agglutination test (SAT) in order to make it available for the routine detection and titration of sperm agglutinins. Serum and seminal plasma samples of 156 subfertile patients were tested by the modified slide agglutination test (MSAT) in two trials. Fifteen per cent of serum and 7.5% of siminal plasma samples gave positive results and MSAT showed excellent reproducibility: a highly significant statistical correlation between the positive titres in the two determinations was observed. One hundred and ten samples were tested simultaneously by the MSAT and the tray agglutination test (TAT). The two tests showed a similar sensitivity with a significant statistical correlation between the positive titres. Using the MSAT the reading of results was easier and more precise. Therefore we propose the MSAT for the routine detection and titration of sperm-agglutinins.

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.

Immunoglobulin classes, secretory component, and sperm agglutinins in semen after vasovasostomy

The immunoglobulin classes of the sperm-agglutinating antibodies in the seminal fluid and serum from four vasovasostomized men, as well as in operatively obtained testis-epididymis fluid from two of them, were investigated by specific solid-phase absorption of IgG, IgM, and IgA. In two patients the major part of the seminal agglutinins was IgA, and in one IgG, indicating that both local production and diffusion of sperm agglutinins from serum to the testis-epididymis compartment may take place. The total levels of immunoglobulins in seminal fluid generally increased after the operation, and IgM was present in two postvasovasostomy samples. This suggests a pathotopic potentiation effect of the vasectomy on the epithelial lining of the testis-epididymis compartment. Comparison of the results of solid-phase absorption with anti-IgA and anti-secretory component (SC) pointed to the presence of "free" SC in postvasovasostomy seminal fluid.

The occurrence of immunoglobulin E in Human seminal plasma

The presence of IgE in human seminal plasma has been explored using two different radioimmunoassay methods. Samples were obtained from 84 patients under investigation for involuntary infertility. Low levels were recorded in seminal plasma (less than 0.05-805 kIU/1) together with a wide scatter of serum values (less than 0.5-956 kIU/1). The incidence of detectable seminal plasma IgE was related to high serum IgE values (P less than 0.001; chi 2-test). Among men reporting allergy problems and who has serum IgE levels above 50 kIU/1 detectable semen IgE was seen in 15 out of 18 patients. Sperm agglutination was observed in 18 men of whom 11 had detectable seminal plasma IgE. The question of whether or not seminal plasma IgE is a plasma transudate or is locally produced as well as its possible function in seminal plasma is discussed.

Postcoital tests and sperm-agglutinating antibodies in men

Postcoital tests (PCTs) were examined from couples where the husbands had circulating head-to-head (H-H) or tail-to-tail (T-T) sperm-agglutinating antibodies. The results were compared with findings in couples without antibodies. The presence of H-H sperm-agglutinating antibodies did not interfere with the outcome of the PCT. High serum titers of T-T sperm-agglutinating antibodies, the presence of such antibodies in the seminal fluid, and/or a strong or complete autoagglutination in the husband's ejaculate markedly reduced the number of invading spermatozoa as well as their survival in the PCT. A moderate titer of T-T sperm-agglutinating antibodies was also reflected in the PCT but low titers did not have any influence on the results.

Immunoglobulin E levels and antisperm antibody titers in infertile couples

Immunoglobulin E (IgE) levels and antisperm antibody titers were determined in samples of serum and seminal plasma from 25 fertile men (Group A), 18 infertile men without measurable immunity to sperm (Group B), and 42 infertile men autoimmune to sperm (Group C), and in samples of serum and cervical and vaginal secretions from 25 fertile women (Group D), 28 infertile women without measurable immunity to sperm (Group E), and 32 infertile women isoimmune to sperm (Group F). Among the men, IgE levels in the serum, measured in international units per milliliter, were elevated in Group C (230 +/- 41, mean +/- SEM) as compared with Groups B (94 +/- 33, P less than 0.05) and A (55 +/- 8, P less than 0.001). In contrast, IgE levels in the seminal plasma in Group C (180 +/- 44) were not significantly different from those in Group B (48 +/- 21), but were higher than those in Group A (8 +/- 2, P less than 0.05). In the women, serum IgE levels were higher (P less than 0.001) in Group F, with isoimmunity to sperm (472 +/- 55), than in Groups E (219 +/- 32) and D (76 +/- 16). Wives of autoimmune husbands had somewhat, though not significantly, higher serum IgE levels (406 +/- 55), than had wives of nonautoimmune husbands (247 +/- 97). These results provide evidence for an elevated IgE response in subjects with significantly elevated antisperm antibody titers.