Identification of antibody-laden sperm by cytofluorometry

Antisperm antibodies: invaluable tools toward the identification of sperm proteins involved in fertilization

The identification of sperm proteins involved in fertilization has been the subject of numerous investigations. Much interest has been dedicated to naturally occurring antisperm antibodies (ASA) and their impact in fertility. Their presence in men and women has been associated with 2-50% of infertility cases. ASA may impair pre- and post-fertilization steps. Experimental models have been developed using sperm proteins as immunogens to evaluate their involvement in sperm function. Our team has pursued investigations to assess ASA presence in biological fluids from patients consulting for infertility and their effect on fertilization. We found ASA in follicular fluids with ability of inducing the acrosome reaction and blocking sperm-zona pellucida interaction and used them to identify sperm entities involved in these events. We generated and utilized antibodies against proacrosin/acrosin to characterize the sperm protease system. We implemented an ELISA to detect proacrosin/acrosin antibodies in human sera and evaluated their impact upon fertility by developing in vitro assays and a gene immunization model. This review presents a summary of ASA history, etiology, current approaches for detection and effects upon fertility. ASA (naturally occurring, generated by animal immunization and/or of commercial origin) are invaluable tools to understand the molecular basis of fertilization, better diagnose/treat immunoinfertility and develop immunocontraceptive methods.

A new multiparameter flow cytometric method for human semen analysis

BACKGROUND

The objectives of this study were (i) to evaluate whether the combined use of Syto 16 and 7-amino-actinomycin-D (7-AAD) allows the detection of sperm apoptosis and (ii) to describe a new multiparameter flow cytometric method to assess simultaneously sperm concentration (SC), viability and apoptosis as well as leukocyte concentration.

METHODS

Semen samples from 68 patients were evaluated according to World Health Organization (WHO) criteria (normal, n=26; abnormal, n=42). The detection of activated caspases before and after betulinic acid (BA) incubation was carried out in 13 semen samples by flow cytometry using fluorescein-labelled inhibitors of caspases (FLICA). A multiparameter flow cytometric analysis was performed in 55 semen samples. Fluorescent microspheres were used to assess SC. Sperm apoptosis was detected by staining sperm with Syto 16 and 7-AAD. Leukocytes were counted using monoclonal anti-CD45.

RESULTS

A significant correlation between the percentage of the spermatozoa with low Syto 16 fluorescence and the percentage of spermatozoa containing activated caspases was found (r=0.68, P=0.0106; n=13). After incubation with BA, an increase of the percentage of apoptotic cells was observed in all samples, using both the Syto 16/7-AAD and the caspase activation methods. There was a good correlation between flow cytometry and optical microscopy for sperm (r=0.98, P < 0.0001) and leukocyte counting (r=0.64, P <0.0001). The percentage of apoptotic sperm was inversely correlated with both SC (r=-0.303, P=0.0246) and morphology (r=-0.384, P=0.0050) but not with motility.

CONCLUSIONS

The combination of Syto 16/7-AAD provides a sensitive assay to detect sperm apoptosis. The multiparameter flow cytometric method described offers the possibility of a simultaneous, simple, rapid and accurate assessment of several semen parameters.

N-terminal region of progesterone receptor B isoform in human spermatozoa

Progesterone is known to act on human spermatozoa by an unidentified membrane receptor. Previous studies have demonstrated the existence of transcripts of conventional progesterone receptor (PR) in sperm RNA; antibodies directed against the C-terminal region of the conventional PR recognize a protein in sperm extracts. The present study aimed at characterizing the sperm PR using probes unique to the N-terminal region of the PR-B isoform. PR-B transcripts that were homologous to the conventional PR were detected in sperm RNA and localized in the midpiece region. Using specific antibody against the N-terminal region of PR-B, strong immunoreactivity was observed on the acrosomal region of digitonin-treated spermatozoa; Western blot analysis revealed a single band of approximately 55 kDa. Immunogold labelling studies using the same antibody localized the protein at the inner acrosomal membrane of testicular spermatids. This antibody blocked the binding of fluorescent-tagged progesterone to digitonin-treated spermatozoa and inhibited the progesterone-mediated kinase activation. The results of the present study gives an insight to speculate that the sperm membrane PR may have homology at the N-terminal region of the conventional PR-B isoform, or the membrane PR protein may share structural motifs that allows progesterone binding and interactions with the antibodies against the conventional PR.

Antisperm antibodies detection by flow cytometry is affected by aggregation of antigen-antibody complexes on the surface of spermatozoa

Flow cytometry (FCM) analysis of live antibody-coated spermatozoa subjected to immunofluorescence staining (FCM test) is considered an objective method for the quantitative detection of antisperm antibodies (ASA). But the cross-linking of cell surface antigen (Ag) with bivalent antibodies and/or antigen-antibody (Ag-Ab) complexes with second antibodies may induce the reorganization of surface components (patching and capping) and result in their shedding from the sperm surface. The present study estimates the relationship between aggregation of Ag-Ab complexes on the sperm surface and the results of indirect FCM test. Swim-up spermatozoa of normozoospermic men were incubated with ASA-positive sera from infertile patients and with second antibodies fluorescein isothiocyanate (FITC)-labelled goat anti-human IgG polyclonal antiserum under different conditions and then analysed by FCM and fluorescence microscopy. It was shown that low temperature, cytochalasin B, excess or lack of the primary and/or secondary antibodies and sperm fixation by paraformaldehyde may inhibit aggregation and shedding of Ag-Ab complexes and dramatically increase ASA quantity determined on the sperm surface. However, inhibition of aggregation on the live sperm surface was observed only in a minority of ASA-positive samples and was poorly reproducible using semen of different donors. A high probability of Ag-Ab complex shedding from the sperm surface during experimental manipulation limits the use of indirect FCM test for quantitative ASA determination.

Leukocyte detection in human semen using flow cytometry

This study set out to establish a new method, using flow cytometry, to evaluate leukocytes in semen. Ejaculates of 59 males, asymptomatic for genitourinary infections, were examined. Routine semen analyses were carried out as well as peroxidase and polymorphonuclear granulocyte-elastase detection. Leukocytes were detected combining flow cytometry and monoclonal antibodies (anti-CD45, anti-CD53). This technique reliably assessed the total number of leukocytes and differentiated subpopulations even at low concentrations. The peroxidase test and elastase determination showed good specificity, but only moderate sensitivity versus flow cytometry combined with monoclonal antibodies. No significant association was observed between semen parameters and leukocytospermia whether evaluated by conventional methods or flow cytometry except for a moderate correlation between spermatozoa and CD53-positive cell concentrations. A first comparison of data from patients grouped on the basis of leukocytospermia (>10(6) white blood cells, WBC/ml) or non-leukocytospermia revealed no significant differences in semen parameters; lowering the threshold value for leukocytospermia to 2x10(5) WBC/ml, sperm concentration was reduced in the group with a low number of WBC identified by monoclonal antibodies. Flow cytometry using monoclonal antibodies was seen to be a simple, reproducible method that enables leukocytes in semen to be accurately detected and to identify WBC subpopulations without preliminary purification procedures.

Characterization of a potent sperm-agglutinating monoclonal antibody and its cognate antigens

OBJECTIVE

To identify sperm antigens that are capable of eliciting infertility-related sperm-agglutinating antibodies.

DESIGN

In vitro laboratory experiments.

SETTING

University research laboratory.

PATIENT(S)

Fertile semen donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Sperm agglutination, immunofluorescence localization, and flow cytometric analysis of surface expression of A36 antigens. Antigen analysis by Western immunoblotting.

RESULT(S)

Monoclonal antibody A36 induced intensive head-to-head, tail-to-tail, and head-to-tail agglutination of motile human spermatozoa. Antigens recognized by A36 were localized on the acrosomal cap and in the principal tail regions of motile, noncapacitated human sperm. Changes in subcellular levels and localization of the A36-recognized epitope occurred after capacitation and acrosomal loss. A36 reacted with a polymorphic series of proteins in Western blots of sperm extracts from humans and various other animal species, including mouse testis extracts. A common 53-kd antigen was recognized by the antibody in the different antigenic preparations.

CONCLUSION(S)

A mouse antibody to human sperm, monoclonal antibody A36, caused intensive agglutination of noncapacitated human spermatozoa and reacted with antigens on the acrosomal cap and in the principal tail regions. Of the multiple polypeptides that were reactive with the monoclonal antibody in sperm extracts from humans and other animal species, a common 53-kd antigen was recognized.

Antisperm antibodies in prepubertal boys and their reactivity with antigenic determinants on differentiated spermatozoa

PROBLEM

Antisperm antibodies induced in prepubertal boys with testicular failures were characterized by using four techniques of antibody detection. The reactivity of circulating antisperm antibodies in prepubertal boys and the reactivity of antibodies in sera samples of adult fertile and infertile males were compared against the same sperm antigenic pools (live or fixed spermatozoa, or sperm antigenic extracts).

METHOD OF STUDY

The incidence of antisperm antibodies in sera samples of 69 prepubertal boys with testicular failures and 21 samples obtained from adult, male individuals was assessed by indirect immunobead binding test (IDIBT), flow cytometry measurement, enzyme-linked immunosorbent assay, and Western blotting. Immunoblot analysis was performed by using sperm extracts of glycosylated and deglycosylated solubilized membrane antigens.

RESULTS

Sera samples were studied in a group composed of healthy prepubertal boys (n = 7) and prepubertal boys with testicular failures (n = 69). Applied tests of antibody detection revealed striking differences in a group of boys with testicular pathology. With IDIBT, 7% of the sera samples were found positive, whereas with flow cytometry measurement, 48% of the sera samples were positive. Immunosorbent assay (fixed sperm) indicated 32% positive cases in the same group. The sera samples were found to be positive in 65% of immunoblotting reactions with glycosylated antigens and in 70% of immunoblotting reactions with deglycosylated antigens. All applied detection assays were clearly negative on sera samples from fertile, adult males. Western immunoblotting indicated an immunodominant antigenic determinant of 58 kDa.

CONCLUSIONS

Tests of antibody detection with the use of live sperm (IDIBT and flow cytometry measurements) presented low sensitivity (8% and 48%, respectively) in a group of prepubertal boys. This observation underlines the difficulties in assigning the prospective prognosis of future fertility status in prepubertal boys with antisperm antibodies.

Detection of antisperm antibodies in seminal plasma by flow cytometry: comparison with the indirect immunobead binding test

OBJECTIVE

To compare flow cytometry with the established indirect immunobead binding test (IBT) for the detection of antisperm antibodies in seminal plasma.

DESIGN

A prospective, comparative study.

SETTING

University-based andrology unit.

PATIENT(S)

One hundred and fifty-eight men with suspected male factor subfertility.

INTERVENTION(S)

Seminal plasma samples were incubated with antisperm antibody-negative donor sperm. Surface-bound antibody was detected with fluorescence-labeled antihuman antibody in the flow cytometry assay or with immunobead-labeled antihuman antibody in the IBT.

MAIN OUTCOME MEASURE(S)

The percentage of sperm that tested positive for surface-bound antibody was determined in the two assays. Seminal plasma was antisperm antibody-positive when > or = 20% of the sperm were antibody-bound, and clinically significant levels were present when > or = 50% of the sperm were antibody-bound.

RESULT(S)

Of 71 samples that were negative by the IMT, 66 (93%) also were negative by flow cytometry. Of 63 samples that had > or = 50% immunobead binding, 55 had equivalent results by flow cytometry. Overall statistical analysis showed a good correlation between the two assays.

CONCLUSION(S)

There is a good correlation between the indirect IBT and indirect flow cytometry for the detection of antisperm antibodies in seminal plasma.

Flow cytometry study on the effect of serum and peritoneal fluid of women on sperm-binding activity of immunoglobulin G antisperm antibodies

OBJECTIVE

To investigate the influence of sera and peritoneal fluids (PFs) from fertile and infertile women on the binding of antisperm antibodies to the surface of spermatozoa.

DESIGN

The immunoglobulin (Ig) G antisperm antibodies binding to the surface of liver spermatozoa was evaluated after their incubation in antisperm antibodies-positive serum from an infertile male in the presence and absence of female sera or PFs.

SETTING

Russian Scientific Center for Obstetrics, Gynaecology, and Perinatology.

PATIENT(S)

Serum and PF samples from fertile and infertile women; antisperm antibodies-positive serum from infertile men; high-quality fresh semen from healthy donors.

INTERVENTION(S)

Serum samples were obtained from fertile and infertile women and from infertile men. Peritoneal fluids were collected during routine laparoscopy.

MAIN OUTCOME MEASURE(S)

The proportion of spermatozoa positive for IgG antibodies and the quantity of antisperm antibodies on the sperm surface measured by flow cytometry (FCM).

RESULT(S)

The addition of sera from fertile or infertile women with endometriosis or pelvic adhesion disease to an IgG antisperm antibodies-positive male serum resulted in significant inhibition of the antisperm antibodies binding to the sperm surface.

CONCLUSION(S)

Sera of fertile as well as infertile woman contain factors that block IgG antisperm antibodies binding to the surface of live spermatozoa.

Review: in vitro spermicidal tests

This review analyzes in vitro spermicidal tests that have been used to evaluate the spermicidal activity of contraceptive products. Special requirements and processes in numerous technologies were also reviewed. Nonoxynol-9 (N-9) was used as an example of a vaginally delivered spermicidal agent, and its spermicidal potency was compared by various spermicidal tests, such as Sander-Cramer, computer-assisted semen analysis, hypoosmotic swelling test, cervical mucus penetration test, and flow cytometry, and advantages and disadvantages of each test were specified. This provides an insight into the different aspects of sperm functionality on which each spermicidal agent exerts its activity. A rationale of the best combination of in vitro spermicidal tests, with particular emphasis on a simple and efficient strategy that targets the complete fertility control, was explained.

Detection of antibodies toward epididymal sperm antigens--an obligatory step in evaluation of human immunologic infertility?

PROBLEM

To test the relative impact of epididymal versus ejaculated sperm in immunologic infertility.

METHOD

Human antibody binding to epididymal and ejaculated spermatozoa was compared by flow cytometry (FCM) since it allows quantitative analysis of viable sperm while ignoring nonsperm cells. To select sera for FCM, GAT, TAT, and ELISA were applied on 145 sera from fertile men, idiopathically infertile and varicocele patients.

RESULTS

All GAT/TAT-positive infertile patients, a representative group of varicocele patients and the fertile control, were assessed by FCM. Higher reactivity toward epididymal sperm revealed 18/22 sera while only four out of them bound to ejaculated sperm stronger than the control. All varicocele sera were positive against epididymal while negative against ejaculated spermatozoa.

CONCLUSIONS

Epididymal sperm antigens may play a predominant role in some cases of immunologic infertility. Such patients might not be adequately diagnosed and respectively treated due to the limitations of diagnostic procedures applying only ejaculated spermatozoa.

Mouse testis cell sorting according to DNA and mitochondrial changes during spermatogenesis

Flow cytometry can measure variations in DNA content and chromatin structure as well as dramatic changes in the mitochondria of germ cells during maturation from spermatogonia to elongated spermatids. Using 10-N nonyl acridine orange (NAO), an inner mitochondrial membrane dye, it is easy to follow mitochondria rearrangements. Mouse testis cells stained with the DNA fluorescent probe propidium iodide (PI) and analyzed by flow cytometry can be discriminated on the basis of their ploidy levels into five main regions corresponding to elongated spermatids, round spermatids, diploid, S-phase, and tetraploid cells. The simultaneous use of PI and NAO demonstrated the presence of cells having low and high mitochondrial content in the haploid, diploid, and tetraploid compartments. Eleven sorting windows were selected from the bivariate analysis (PI/NAO) and the corresponding cells were identified by microscopic observation. Cells were also discriminated by two parameter analysis of DNA content vs. cell diameter. The definition of seven different regions allowed us to determine NAO or rhodamine 123 (Rh 123) uptakes in each compartment. We observed that the ratio (Rh 123/NAO) dramatically changed according to the progression of cell differentiation which occurs during spermatogenesis.

Antibody-induced changes on rabbit sperm surface inhibit gamete interaction

Interaction of specific ligands with cell surface molecules may induce reorganization of surface components. A monoclonal antibody (B-12) against sperm surface antigens of 40kDa size induced molecules on the plasma membrane overlying the acrosome of rabbit sperm to cluster in small aggregates at 0 degree C (patching). At an elevated temperature of 37 degrees C these clusters of antigen antibody complexes collected into a large aggregate on one pole of the cell forming a cap (capping). This cap-like structure showed a reduction in size over a period of time and eventually disappeared from the sperm surface. Inhibition of capping by sodium azide indicated that it is an energy-dependent process. Patching of antigens did not require energy. Involvement of sperm head cytoskeleton in the process of capping was evident from potentiation of cap formation by cytoskeleton disrupting agents like cytochalasin B and D. Patching of antigen antibody complexes was not affected by either of the agents. The loss of antigen antibody complexes from sperm surface was mainly due to shedding of the complexes in the surrounding media. Sperm with patches of antigen antibody complexes did not adhere to oocytes. Sperm from the group where a majority of the sperm were denuded of the antigen antibody complexes also did not bind to oocytes.

Flow cytometric evaluation of the acrosome reaction of human spermatozoa: a new method using a photoactivated supravital stain

A flow cytometric assay using a double-stain method for the measurement of the acrosome reaction of human spermatozoa is described. The use of a stable photoactivated stain, ethidium monoazide, allowed evaluation of the viability of spermatozoa. This stain was more stable in fixed samples than propidium iodide, which is not bound covalently to DNA and is therefore removed readily during the washing procedure. The permeabilized acrosome was labelled with Pisum sativum agglutinin conjugated with fluoroisothiocyanate. Since this lectin binds to the acrosome and acrosomal contents, a decrease in the fluorescence intensity allows the cytometric evaluation of the acrosome reaction. Microscopic analysis and flow cytometric analysis were well correlated and cell sorting was performed to ensure the homogeneity of each different subpopulation encountered.

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.

Selective expression of a progesterone receptor on the human sperm surface

OBJECTIVE

To visualize progesterone (P) binding sites on the sperm surface, examine the relationship between hormone binding and hormone action (acrosome reaction), and determine the size of the hormone-responsive sperm subpopulation.

DESIGN

Kinetic analysis of P binding was combined with the assessment of the hormone effect using a fluorescent acrosomal marker.

SETTING

Private hospital, medical research center, and a university-based andrological laboratory.

PATIENTS, PARTICIPANTS

Sperm samples were from healthy volunteers with normal spermiogram values.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Progesterone binding was analyzed by fluorescence microscopy and flow cytometry using P coupled to fluorescein isothiocyanate-labeled bovine serum albumin. Tetramethylrhodamine isothiocyanate-labeled Pisum sativum agglutinin was used as acrosomal marker in double-labeling experiments.

RESULTS

After in vitro capacitation, only few spermatozoa (approximately 10%) were able to bind P to the cell surface, but most of these cells subsequently generated the acrosome reaction in response to hormone binding.

CONCLUSIONS

The expression of P receptor sites on the human sperm surface is a major factor controlling the P-induced acrosome reaction. Further studies are warranted to explore if defective expression of the receptor can compromise fertility.

The predominance of IgG1 and IgG3 subclass antisperm antibodies in infertile patients with serum antisperm antibodies

Mouse monoclonal antibodies (MAb) specific for each of the four human IgG subclasses and immunofluorescence flow cytometry were used to evaluate the subclass of the IgG antibody response to sperm in serum samples from 13 men and 6 women with a high titer (greater than 1:15,625) of IgG antisperm antibodies (ASA] determined by an indirect immunobead test. Five sera without ASA were also studied as a control. All 19 (100%) of the ASA-positive sera contained immunoglobulin (Ig)G ASA of the IgG1 and IgG3 subclasses. A 1:1 correlation was observed between the presence of IgG1 and IgG3 ASA. IgG2 was essentially undetectable, while IgG4 reactivity, although less intense than IgG1 and IgG3, was more prominent in the sera from the five vasectomized men. The ability of the IgG1 and IgG3 ASA-positive sera to deposit complement (C) on sperm was demonstrated by the concomitant binding to antibody-laden sperm of polyclonal antibodies to the membrane attack complex (C5b-9) of C. Both C-fixing and non-C-fixing ASA-positive sera were found to possess IgG1 and IgG3 antisperm antibodies. The predominance of IgG1 and IgG3 subclasses suggested a T-cell dependent immune response to sperm antigens.

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.

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.

ABH blood group antigens in human semen

Human sperm, erythrocytes, and seminal plasma from the blood and semen of 20 men of known ABH, Lewis, and secretor phenotypes were assayed for ABH blood group antigens. A 1:1 correlation was found between the presence of ABH antigens in seminal plasma and on sperm and if the man had a secretor phenotype. Sperm from nonsecretors or from men of dissimilar ABO blood type could adsorb A antigen when incubated with A antigen-containing seminal plasma. The level of ABH antigens in seminal plasma correlated with the level of ABH antigens on the sperm surface. ABH antigens in semen were present only on a minority of spermatozoa as detected by flow cytometry, and the majority of these sperm were not in the swimup fraction. ABH antigens were not present on sperm within the seminiferous tubules of human testicular material. It was hypothesized that ABH antigens found on human sperm were adsorbed from seminal plasma on a minority of the sperm in an ejaculate.

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.

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.