The role of antisperm antibodies in infertility

Anti-sperm Antibodies as an Increasing Threat to Male Fertility: Immunological Insights, Diagnostic and Therapeutic Strategies

It is a fact that sperm possess antigenic properties. Substantial scientific research suggests that specific antibodies that attach to sperm antigens can induce infertility in both humans and other species. Antisperm antibodies (ASA) represent a significant etiology of infertility in humans, leading to immunoinfertility. The association between ASA and infertility is multifaceted. The observation of sperm agglutination, although not conclusive for the diagnosis of immunological infertility, may suggest the presence of ASA. Nevertheless, ASA may also manifest in the lack of any sperm agglutination. Managing ASA from an andrological perspective depends on the underlying cause and the specific approaches healthcare professionals adopt. The precise etiology of male infertility resulting from ASA remains unclear. Current research has examined the impact of ASA and its prevalence among infertile males to understand the relationship between ASA and changes in semen parameters. However, the findings have been inconclusive. Numerous techniques have been documented for the management of immunoinfertility. This review examines the importance of ASA in the context of infertility, encompassing the postulated mechanisms underlying the development of ASA, the various assays employed for detecting them, and the available treatments.

Sperm tendency to agglutinate in motile bundles in relation to sperm competition and fertility duration in chickens

A unique sperm behavior was observed in Egyptian chickens. Sperm showed a tendency to agglutinate forming motile thread-like bundles. Sperm agglutination behavior, kinematics, and some morphometric measures were studied in relation to sperm competition and fertility duration in Sharkasi and Dandarawi chickens. Sperm tendency to agglutinate was assessed by examining sperm morphology using scanning electron microscopy, Acridine orange-stained semen smears using fluorescence microscopy, and recording videos of sperm under phase contrast microscope. Sperm velocity and morphometric measures were evaluated using image-J software. To assess sperm competition, Sharkasi and Dandarawi hens were artificially inseminated by semen pools possessing equal number of Sharaksi and Dandarawi sperm. Artificial insemination was repeated ten times. The eggs obtained were incubated, and the hatchlings were discriminated as descending from Sharkasi or Dandarawi fathers according to their phenotype. To assess the fertility duration, Sharkasi and Dandarawi hens were inseminated by semen collected from roosters of the same strain. Eggs were collected for a period of 28 days post-insemination and incubated. Sharkasi spermatozoa showed higher tendency to agglutinate forming longer and thicker motile bundles. No significant differences were observed in sperm curvilinear and straight line velocity and in sperm morphometric measures between Sharkasi and Dandarawi chickens. Sharkasi roosters fathered 81.6% and 67.7% of the hatchlings produced by Sharkasi and Dandarawi mothers, respectively. The fertility period in Sharkasi and Dandarawi was 22 and 14 days, respectively. We suggest that the differences seen in sperm competitiveness and fertility duration can be attributed to sperm agglutination behavior.

The prognostic value of seminal anti-sperm antibodies screening in men prepared for ICSI: a call to change the current antibody-directed viewpoint of sperm autoimmunity testing

Aims

We aimed to prospectively evaluate the prognostic value of seminal anti-sperm antibodies (ASA) screening in couples prepared for intracytoplasmic sperm injection (ICSI).

Methods

A prospective comparative study was conducted, including 184 non-azoospermic infertile men scheduled for ICSI. For each patient, detection of ASA in seminal plasma using the ELISA technique was done and its relation to standard semen parameters and ICSI outcomes, including fertilization, embryo development, and pregnancy rates, was analyzed.

Results

Sperm count, motility, and morphology were negatively affected by existence of seminal ASA (p = 0.012, 0.006, and 0.011, respectively). However, no statistically significant difference was detected between patients with positive and negative seminal ASA regarding the median values of fertilization (56.3% versus 66.7%, p = 0.091), percentage of couples with grade A embryo development (91.4% versus 89.9%, p = 0.520), and pregnancy rates (31.4% versus 32.2%, p = 0.98) after ICSI.

Conclusion

ICSI seems able to overcome the problem of ASA in semen. The routine screening of ASA in men prepared for ICSI has no additional prognostic value and cannot be recommended for the time being, until more specific antigen-concerned testing can be developed.

Rheumatology-led pregnancy clinic: men perspective

The birth of reproductive rheumatology as a subject of interest in rheumatology has led to improvement of clinical care for patients living with autoimmune rheumatic diseases and paved the way towards setting a specialized pregnancy service within the standard rheumatology practice. In contrast to women, where there has been wealth of literature regarding pregnancy, lactation, and birth outcomes, there is not as much focusing on male sexual health and outcomes among inflammatory arthritis patients. Challenges such as decrease ability to conceive, impaired fertility, erectile dysfunction, and other sexual problems have been raised by male patients living with autoimmune rheumatic diseases. This broad scope gives the reproductive health concept in men another expansion with views to include sexual health problems screening among men attending the standard outpatient rheumatology clinics. This article adds to the paucity of real-life experience and aims at discussing the sexual health from the men perspective and provides a practical approach towards screening, and assessment of men living with autoimmune diseases in standard day to day practice.

Reproductive immunology in viviparous mammals: evolutionary paradox of interactions among immune mechanisms and autologous or allogeneic gametes and semiallogeneic foetuses

Literally, reproductive immunology was born in bovine on-farm reproduction where seminal experiments intended for developing methods for embryo transfer in cattle were performed. Actually, these experiments led to two of major concepts and fundamental principles of reproductive immunology using the bovine species as a model for biomedical research, namely the concept of acquired immunological tolerance and the paradox of the semiallogeneic bovine foetus whereby such organism can develop within an immunologically competent host. Peter Medawar, a scientist who together with Frank Macfarlande Burnet shared the 1960 Nobel Prize in physiology or medicine for discovery of acquired immunological tolerance, while studying dizygotic cattle twins, thereby giving birth to reproductive immunology. Also, these findings significantly influenced development of organ transplants and showed that using farm animals as models for studying transplantation immunology had general relevance for mammalian biology and health including those of humans. However, the interest for further research of the fascinating maternal immune influences on pregnancy and perinatal outcomes and of the prevention and treatment of immunologically mediated reproductive disorders in viviparous mammals of veterinary relevance by veterinary immunologists and reproductive clinicians have been very scarce regarding the application of nonspecific immunomodulatory agents for prevention and treatment of subfertility and infertility in pigs and cattle, but still broadening knowledge in this area and hold great potential for improving such therapy in the future. The aim of the current overview is to provide up-to-date information and explaining/translating relevant immunology phenomena into veterinary practice for specialists and scientists/clinicians in reproduction of animals.

Potential mechanisms of SARS-CoV-2 action on male gonadal function and fertility: Current status and future prospects

The novel coronavirus was recognised in December 2019 and caught humanity off guard. The virus employs the angiotensin‐converting enzyme 2 (ACE2) receptor for entry into human cells. ACE2 is expressed on different organs, which is raising concern as to whether these organs can be infected by the virus or not. The testis appears to be an organ enriched with levels of ACE2, while the possible mechanisms of involvement of the male reproductive system by SARS‐CoV‐2 are not fully elucidated. The major focus of the present studies is on the short‐term complications of the coronavirus and gains importance on studying the long‐term effects, including the possible effects of the virus on the male reproductive system. The aim of this review was to provide new insights into different possible mechanisms of involvement of male gonads with SARS‐CoV‐2 including investigating the ACE2 axis in testis, hormonal alterations in patients with COVID‐19, possible formation of anti‐sperm antibodies (ASA) and subsequently immunological infertility as a complication of SARS‐CoV‐2 infection. Finally, we suggest measuring the sperm DNA fragmentation index (DFI) as a determiner of male fertility impairment in patients with COVID‐19 along with other options such as sex‐related hormones and semen analysis. Invasion of SARS‐CoV‐2 to the spermatogonia, Leydig cells and Sertoli cells can lead to sex hormonal alteration and impaired gonadal function. Once infected, changes in ACE2 signalling pathways followed by oxidative stress and inflammation could cause spermatogenesis failure, abnormal sperm motility, DNA fragmentation and male infertility.

Engineering monoclonal antibody-based contraception and multipurpose prevention technologies†

Sexually transmitted infections are highly prevalent, and over 40% of pregnancies are unplanned. We are producing new antibody-based multipurpose prevention technology products to address these problems and fill an unmet need in female reproductive health. We used a Nicotiana platform to manufacture monoclonal antibodies against two prevalent sexually transmitted pathogens, HIV-1 and HSV-2, and incorporated them into a vaginal film (MB66) for preclinical and Phase 1 clinical testing. These tests are now complete and indicate that MB66 is effective and safe in women. We are now developing an antisperm monoclonal antibody to add contraceptive efficacy to this product. The antisperm antibody, H6-3C4, originally isolated by Shinzo Isojima from the blood of an infertile woman, recognizes a carbohydrate epitope on CD52g, a glycosylphosphatidylinositol-anchored glycoprotein found in abundance on the surface of human sperm. We engineered the antibody for production in Nicotiana; the new antibody which we call "human contraception antibody," effectively agglutinates sperm at concentrations >10 μg/ml and maintains activity under a variety of physiological conditions. We are currently seeking regulatory approval for a Phase 1 clinical trial, which will include safety and "proof of principle" efficacy endpoints. Concurrently, we are working with new antibody production platforms to bring the costs down, innovative antibody designs that may produce more effective second-generation antibodies, and delivery systems to provide extended protection.

Male fertility potential alteration in rheumatic diseases: a systematic review

BACKGROUND

Improved targeted therapies for rheumatic diseases were developed recently resulting in a better prognosis for affected patients. Nowadays, patients are living longer and with improved quality of life, including fertility potential. These patients are affected by impaired reproductive function and the causes are often multifactorial related to particularities of each disease. This review highlights how rheumatic diseases and their management affect testicular function and male fertility.

MATERIALS AND METHODS

A systematic review of literature of all published data after 1970 was conducted. Data was collected about fertility abnormalities in male patients with systemic lupus erythematosus, rheumatoid arthritis, dermatomyositis, ankylosing spondylitis, Behçet disease and gout. Two independent researchers carried out the search in online databases.

RESULTS

A total of 19 articles were included addressing the following diseases: 7 systemic lupus erythematosus, 6 Behçet disease, 4 ankylosing spondylitis, 2 rheumatoid arthritis, 2 dermatomyositis and one gout. Systemic lupus erythematosus clearly affects gonadal function impairing spermatogenesis mainly due to antisperm antibodies and cyclophosphamide therapy. Behçet disease, gout and ankylosing spondylitis patients, including those under anti-TNF therapy in the latter disease, do not seem to have reduced fertility whereas in dermatomyositis, the fertility potential is hampered by disease activity and by alkylating agents. Data regarding rheumatoid arthritis is scarce, gonadal dysfunction observed as consequence of disease activity and antisperm antibodies.

CONCLUSIONS

Reduced fertility potential is not uncommon. Its frequency and severity vary among the different rheumatic diseases. Permanent infertility is rare and often associated with alkylating agent therapy.

Antisperm antibodies and fertility association

OBJECTIVE

To evaluate the relation between antisperm antibodies (ASA) and human fertility by reviewing the scientific literature of the last 45 years.

METHODS

We carried out a review of scientific literature about antisperm antibodies and infertility published in spanish or english in databases as Pubmed, Medline, Scielo, some books and another gray literature include information related to this review and that is published in the last 45 years.

SUMMARY OF EVIDENCE

Infertile couples suffer infertility by immunological mechanisms mainly by the presence of antisperm antibodies ASA in blood, semen or cervicovaginal secretions; the formation of ASA in men and women may be associated with disturbance in immunomodulatory mechanisms that result in functional impairment of sperm and thus its inability to fertilize the oocyte.

CONCLUSION

Immunological infertility caused by ASA is the result of interference of these antibodies in various stages of fertilization process, inhibiting the ability of interaction between sperm and oocyte.

Antisperm immunity and infertility

Immunoinfertility is one of several causes of infertility in humans. Although progress on antisperm immunity and infertility has advanced during the past three decades, the nature of a real antisperm antibody (ASA) is still poorly understood. Dozens of sperm antigens have been isolated and characterized in association with infertility. However, it is difficult to identify a single predominant target antigen that could interact with all the ASAs. There are some protective mechanisms preventing ASA production in males and females. As chronic infection, vasectomy and vasovasostomy, heavy metals, and testicular cancer and torsion may induce the production of ASAs, they may be responsible for decreased motility and sperm penetration of cervical mucus, and the blockage of the acrosome reaction and the sperm-egg interaction. Many ASA assay methods have been developed, each with advantages and disadvantages. Efforts for the treatment of ASA-mediated infertility have been attempted. However, current therapy for ASA-associated infertility is almost empiric and largely unproven.

Is there a role of autoimmunity in implantation failure after in-vitro fertilization?

PURPOSE OF REVIEW

The process of implantation involves the interaction of the human blastocyst and the uterine epithelium. Several autoimmune factors have been implicated to have an influence on implantation failure.

RECENT FINDINGS

Recent studies have investigated the role of autoimmune factors in implantation in women undergoing in-vitro fertilization. Antiphospholipid antibodies are identified more frequently in women undergoing in-vitro fertilization, but their presence does not appear to influence the outcome of pregnancy, miscarriage, or live birth rates. Antithyroid antibodies are commonly found in women of reproductive age, but implantation rates and miscarriage rates are not altered when women have normal thyroid function. Antinuclear antibodies may be a marker for underlying autoimmune disease when coupled with certain signs and symptoms, but low-titer antibodies do not influence in-vitro fertilization outcome. Antisperm antibodies are more often associated with fertilization failure when found in high titers in seminal plasma, in sperm, or in the mucosal immune system of women. Antisperm antibodies are uncommon but most often associated with ovarian hypofunction.

SUMMARY

Implantation is characterized by the interaction of two immunologically and genetically distinct tissues. During implantation, local and systemic immune factors, cytokines, and growth factors may interact with adhesion molecules and other matrix-associated proteins, glycoproteins, and peptides.

EFFECTS OF TESTICULAR FIXATION ON OXIDATIVE STRESS-RELATED PARAMETERS IN PREPUBERTAL RAT TESTIS

The goal of orchiopexy is to provide adequate scrotal fixation to prevent recurrent torsion of the testis and the spermatic cord or ascent of the testis, to be achieved with minimal trauma to the testis. Forty-two prepubertal male Sprague-Dawley rats were equally distributed into 6 groups (1 SHAM + 5 Operation). In operational groups, two lateral sutures were placed near the upper and lower pole of the testis passing through the tunica albuginea with 4-zero polyglactin suture in the transverse axis of the testis. At the 1st-3rd-7th-15th and 30th postoperative days, bilateral orchiectomy was performed, then malondialdehyde (MDA), nitrite, superoxide dismutase (SOD) and glutathion peroxidase (GPx) values were measured in testicular tissue homogenates. MDA and nitrite levels increased, while GPx and SOD levels diminished, statistically significant in both ipsilateral and contralateral testicular tissue homogenates. Prepubertal testicular fixation causes overproduction of the lipid peroxidation end product and free radicals while heavy consuming anti-oxidant reserve systems in both ipsilateral and contralateral testicular tissue. These results clearly reveal the extent of the testicular deterioration due to suture fixation technique.

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.

Equatorial segment protein (ESP) is a human alloantigen involved in sperm-egg binding and fusion

The equatorial segment of the sperm head is known to play a role in fertilization; however, the specific sperm molecules contributing to the integrity of the equatorial segment and in binding and fusion at the oolemma remain incomplete. Moreover, identification of molecular mediators of fertilization that are also immunogenic in humans is predicted to advance both the diagnosis and treatment of immune infertility. We previously reported the cloning of Equatorial Segment Protein (ESP), a protein localized to the equatorial segment of ejaculated human sperm. ESP is a biomarker for a subcompartment of the acrosomal matrix that can be traced through all stages of acrosome biogenesis (Wolkowicz et al, 2003). In the present study, ESP immunoreacted on Western blots with 4 (27%) of 15 antisperm antibody (ASA)-positive serum samples from infertile male patients and 2 (40%) of 5 ASA-positive female sera. Immunofluorescent studies revealed ESP in the equatorial segment of 89% of acrosome-reacted sperm. ESP persisted as a defined equatorial segment band on 100% of sperm tightly bound to the oolemma of hamster eggs. Antisera to recombinant human ESP inhibited both oolemmal binding and fusion of human sperm in the hamster egg penetration assay. The results indicate that ESP is a human alloantigen involved in sperm-egg binding and fusion. Defined recombinant sperm immunogens, such as ESP, may offer opportunities for differential diagnosis of immune infertility.

Immunisation of the male tammar wallaby (Macropus eugenii) with spermatozoa elicits epididymal antigen-specific antibody secretion and compromised fertilisation rate

Immunocontraception has been proposed as an effective and humane means of controlling overabundant kangaroo populations in Australia. We have examined the feasibility of using a sperm-based vaccine for this purpose using a model macropod species, the tammar wallaby (Macropus eugenii). This study has demonstrated immunocontraception in a marsupial species following immunisation of males with homologous spermatozoa. Serum anti-sperm IgG titres were associated with a significant reduction in fertilisation rates following mating with superovulated female wallabies. Antigen-specific IgG penetrated the reproductive tract at the rete testis and bound spermatozoa in vivo. IgG was detected bound to the acrosome and midpiece regions of both epididymal and ejaculated spermatozoa. The absence of adverse testicular pathology and sperm movement effects suggests that contraception may have been achieved by antibody-mediated blocking of sperm surface antigens essential for fertilisation. This study demonstrates that a contraceptive vaccine targeting sperm antigens has potential for fertility control in male macropods.

Contraceptive vaccines targeting sperm

Overpopulation is a global problem of significant magnitude, with grave implications for the future. Development of new contraceptives is necessary, as existing forms of birth control are unavailable, impractical and/or too expensive for many individuals due to sociological, financial or educational limitations. Immunocontraception and, in particular, the targeting of antibodies to sperm-specific antigens implicated in sperm-egg binding and fertilisation offers an attractive approach to control fertility. Sperm-specific antibodies may impair fertility by inhibiting sperm motility, by reducing penetration of the cervical mucus by sperm, or by interfering in sperm capacitation or the acrosome reaction; alternatively, antisperm antibodies may invoke the complement cascade, resulting in sperm lysis. The antibodies raised against sperm-specific antigens have proved to be extremely effective at reducing sperm-egg interactions in vitro; fertility trials in subhuman primates will eventually be needed to prove the effectiveness of the sperm antigens in terms of contraceptive efficacy before trials in humans can be justified. In addition, existing and emerging strategies (such as sperm proteomics, the determination of molecular and structural details of sperm proteins, and the modelling of protein-ligand interactions using X-ray and/or NMR structures to name a few) are expected to provide the experimental foundation for the design of small molecule inhibitors with antifertility effects. The technology underpinning vaccine development is constantly being developed and the introduction of DNA/RNA vaccines is certain to impact upon the field of immunocontraception.

Search for peptide sequences involved in human antisperm antibody-mediated male immunoinfertility by using phage display technology

The aim of the present study was to delineate peptide sequences against which antisperm antibodies (ASA) are raised in immunoinfertile men. Using the phage display technology, seven unique and novel dodecamer amino acid sequences were identified that reacted with the sera of immunoinfertile men. The peptides were synthesized based upon these amino acid sequences and examined for their immunoreactivity with sera from ASA-positive immunofertile men (n = 15) and ASA-negative fertile men (n = 18) for IgM, IgG, and IgA class of antibody in the enzyme-linked immunosorbent assay (ELISA). All the seven synthetic peptides showed a significantly (P < 0.001) higher mean absorbance values for IgG and/or IgA class of antibody with the immunoinfertile sera compared to fertile control sera. Three of the seven peptides demonstrated a stronger reaction (>2 SD units) with 27%-40% of immunoinfertile sera compared to fertile controls. These peptide sequences may find applications in the specific diagnosis and treatment of immunoinfertility and in contraceptive vaccine development. The phage display technique provides an exciting and novel technology to delineate sperm epitopes involved in immunoinfertility.

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.

Mumps epididymo-orchitis with prolonged detection of virus in semen and the development of anti-sperm antibodies

Epididymo-orchitis is the most common complication of mumps in post-pubertal men. A case of MMR vaccine failure, in whom mumps and mumps-associated unilateral epididymo-orchitis developed, is presented in this article. Mumps virus was isolated from the semen 14 days after onset and mumps RNA was detected in semen for up to 40 days using RT-PCR. Epididymo-orchitis was associated with transient but significant reduction in sperm count and severe abnormalities in sperm morphology. It also led to the appearance of anti-sperm antibodies, which may have potential long-term adverse effects on the patient's fertility. Sequencing of the SH gene of the virus showed this to be a new mumps genotype distinct from the virus circulating currently in the UK.

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.

Validity of a rapid assay for antisperm antibodies in semen

OBJECTIVE

To determine the validity of a rapid assay for antisperm antibodies in semen.

DESIGN

Prospective comparison of the results of standard and rapid antisperm antibody assays performed simultaneously.

SETTING

Tertiary care infertility center.

PATIENT(S)

Couples who presented for infertility evaluation.

INTERVENTION(S)

Semen analysis and measurement of antisperm antibodies in semen using a standard and a rapid immunobead binding test (IBT).

MAIN OUTCOME MEASURE(S)

[1] Comparison of sperm parameters between semen-containing antisperm antibodies and semen free of antisperm antibodies. [2] Validation of the rapid test by calculation of sensitivity, specificity, positive and negative predictive values of the rapid assay using the standard assay as a gold standard. [3] Cost comparison of the standard and rapid test.

RESULT(S)

[1] Nine semen specimens with antisperm antibodies had a significantly lower sperm concentration, motility, and total motile fraction compared to 44 specimens without antisperm antibodies. Also, specimens with antisperm antibodies had a significantly higher percentage of vibratory sperm and percent of bound antisperm antibodies. The strict morphology, liquefaction time, semen volume, and white blood cell concentration were no different between the two groups. [2] Using a threshold of > or =12% of bound antisperm antibodies in the rapid assay, the sensitivity, specificity, positive and negative predictive values of the test are 100% when correlated with a threshold of > or =20% in the standard assay. Increasing the threshold in the standard assay decreases the specificity and positive predictive value of the rapid assay but not the sensitivity and the negative predictive value. [3] The cost of the rapid assay was 16% that of the standard test and its performance took 20% of the time it took to set and perform the standard test.

CONCLUSION(S)

A rapid test for antisperm antibodies is valid, reliable, and more cost and labor effective than a standard IBT.

Comprehensive office evaluation in the new millennium

The success of a comprehensive office-based evaluation of male-factor infertility depends on the physician's thorough understanding of risk assessment in the history, identification of pertinent physical examination findings, and correct assessment of laboratory data. Office-based ultrasonographic techniques have already increased the urologist's ability to visualize suspected anatomic abnormalities, and the use of functional tests of sperm has given greater depth to the limited, but essential, prognostic capabilities of the routine semen analysis.

A comparative study of leukocyte counts and disease risk in primates

Little is known about how the risk of disease varies across species and its consequences for host defenses, including the immune system. I obtained mean values of basal white blood cells (WBC) from 100 species of primates to quantify disease risk, based on the assumption that higher baseline WBC counts will be found in species that experience greater risk of acquiring infectious disease. These data were used to investigate four hypotheses: disease risk is expected to increase with (1) group size and population density; (2) greater contact with soil-borne pathogens during terrestrial locomotion; (3) a slow life history; and (4) increased mating promiscuity. After controlling for phylogeny, WBC counts increased with female mating promiscuity, as reflected in discrete categories of partner number, relative testes mass, and estrous duration. By comparison, the social, ecological, and life-history hypotheses were unsupported in comparative tests. In terms of confounding variables, some WBC types were associated with body mass or activity period, but these variables could not account for the association with mating promiscuity. Several factors may explain why hypotheses involving social, ecological, and life-history factors went unsupported in these tests, including the role of behavioral counterstrategies to disease, restrictions on female choice of mating partners, and the effect of transmission mode on parasite strategies and host defenses.

Decreased suppression of antibody-dependent cellular cytotoxicity by seminal plasma in unexplained infertility

OBJECTIVE

To determine whether seminal plasma (SP) from unexplained infertile males has different suppressive activity on antibody-dependent cellular cytotoxicity (ADCC) than SP from fertile males or SP from males of couples with known infertility factor.

DESIGN

Comparative clinical/experimental study.

SETTING

In vitro fertilization program in a university hospital and a hospital research laboratory.

PATIENT(S)

A total of 245 SP samples from 174 infertile and 16 fertile couples were compared.

INTERVENTION(S)

SP suppression of ADCC was measured by using human 51chromium-labeled red blood cells (RBC), sensitized with IgG-rabbit-anti-human-RBC as targets and peripheral blood lymphocytes as effector cells.

MAIN OUTCOME MEASURE(S)

Suppressive activity of each sample was determined by calculating 51Cr-release in the presence and absence of SP.

RESULT(S)

When analyzed with respect to sperm number, motility, and morphology, suppressive activities of samples with normal semen analyses (n = 142) were significantly higher (x = 37% +/- 14%) than suppressive activities of abnormal samples (n = 103; x = 32% +/- 13%). There was no strong correlation of suppressive activity to other semen parameters. Within the andrologically normal males, SP from the unexplained infertile couples (n = 15) showed significantly lower suppressive activity (x = 24% +/- 11%) compared with the SP from fertile males (n = 16; x = 35% +/- 13%) and from couples with female infertility factor (n = 65; x = 39% +/- 14%).

CONCLUSION(S)

Loss of suppressive activity is associated with unexplained infertility, even in male patients who previously were considered normal by traditional methods of semen analysis.

Antisperm antibodies associated with infertility: properties and encoding genes of target antigens

Infertility among couples of reproductive age is a perplexing condition when the cause is indeterminate. These cases are classified as unexplained infertility. In a subset of subjects, antisperm antibodies with sperm agglutinating and/or immobilizing activities have been detected in the blood or fluids of the reproductive tract. These cases are designated as immunologic infertility although a cause and effect relationship of the antibodies to infertility has not been established. In this review, seven target sperm antigens to antibodies associated with infertility and their encoding genes are described. The antisperm antibodies (ASAs) examined were obtained from infertile women or were monoclonal antibodies (mAb) raised against human sperm proteins. All the ASAs studied possessed potent sperm agglutinating and/or immobilizing activities. The target antigens were isolated from human and other mammalian sperm, and the encoding genes identified. The seven antigens are YWK-II, BE-20, rSMP-B, BS-63 (nucleoporin-related), BS-17 (calpastatin), HED-2 (zyxin), and 75- kDa. Each antigen is a distinct and separate entity and is produced by different cells of the reproductive tract, (e.g., germ cells, epididymal epithelial cells, and Sertoli cells). No single predominant target component has been found to interact with the ASAs. It is proposed that immunologic infertility is the consequence of the combined actions of multiple ASAs in immobilizing and/or agglutinating spermatozoa, blocking spermegg interaction, preventing implantation, and/or arresting embryo development.

Cloning of a glucose phosphate isomerase/neuroleukin-like sperm antigen involved in sperm agglutination

The mouse monoclonal antibody (mAb) A36 produced by us and shown to induce extensive, "tangled" sperm agglutination was used to isolate cDNAs encoding its cognate antigen. Three overlapping cDNA clones specifically recognized by the mAb were isolated from a human testis cDNA expression library in lambdagt11. Sequencing of these cDNAs yielded the complete nucleotide sequence of a 3-kilobase cDNA that encodes the mAb-related polypeptide, designated sperm antigen-36 (SA-36), composed of 558 deduced amino acids. SA-36 cDNA contained a 5' untranslated region of 234 nucleotides (nt), an open reading frame of 1674 nt, and a 3' untranslated region of 1138 nt. SA-36 cDNA displayed > 99% homology to glucose phosphate isomerase (GPI)/neuroleukin (NLK) mRNA. This surprising homology was confirmed in Western blots demonstrating that mAb A36 reacted specifically with GPI obtained from rabbit muscle and from baker's yeast. Moreover, polyclonal, monospecific antibodies produced against beta-galactosidase/SA-36-3 fusion protein stained human spermatozoa and caused intensive agglutination of these cells in a manner similar to that with the mAb. Taken together, the data presented here demonstrated that mAb A36 cognate sperm surface antigen, encoded by SA-36 cDNA, is a GPI/NLK-like protein involved in sperm agglutination.

Antisperm autoantibody response is reduced by early repair of a severed vas deferens in the juvenile rat

OBJECTIVE

To determine whether antisperm autoantibody production after prepubertal vas injury is influenced by immediate repair of the vas compared to delay of the reanastomosis until sexual maturity.

DESIGN

Animal study comparing early repair, late repair, and sham-operated groups.

SETTING

Research laboratory in a medical school.

PATIENT(S)

Lewis rats.

INTERVENTION(S)

After division of the vas deferens in juvenile rats, animals in an early repair group had the vasa repaired immediately by using an absorbable intraluminal stent. Animals in a late repair group had vasa obstructed by ligation until after puberty, when they underwent microsurgical vasovasostomy (age 60 days).

MAIN OUTCOME MEASURE(S)

Antisperm antibodies were assayed by ELISA. The weights of reproductive organs were determined, and samples of testis were studied by light microscopy.

RESULT(S)

The antisperm antibody response was less when the vas was repaired immediately than if the repair was delayed until after puberty. There was a low incidence of testicular alteration in the repair groups and none in sham-operated animals.

CONCLUSION(S)

If the vas deferens is injured or obstructed prepubertally, there may be a benefit to considering immediate repair to reduce the likelihood of developing antisperm autoantibodies, which have been associated with reduced fertility.

Sperm mitochondria-associated cysteine-rich protein (SMCP) is an autoantigen in Lewis rats

A common repertoire of rat sperm antigens have previously been identified by Western blotting of sperm proteins with sera obtained after vasectomy or isoimmunization with sperm. Aside from a determination of their apparent masses, however, the biochemical characteristics of these antigens have remained unknown. In this study, a rat testis cDNA expression library was screened with polyclonal antibodies obtained from rats immunized with isologous spermatozoa to identify and sequence a full-length clone encoding rat sperm mitochondria-associated cysteine-rich protein (SMCP). The open reading frame of SMCP was expressed in the pET22b vector, and recombinant SMCP (rec-SMCP) was purified. Sera from rats that had been vasectomized or hyperimmunized with isologous sperm specifically recognized rec-SMCP whereas preimmune sera from these experimental groups did not react. Rabbit antiserum produced to rec-SMCP recognized rec-SMCP on Western blots and precisely immunolocalized SMCP to the mid-piece of rat sperm. On Western blots against sperm extracts, the rabbit antibody recognized a major protein band of approximately 22-25 kDa that co-migrated with bands of identical mass that were recognized by sera from hyperimmune or vasectomized rats. These findings demonstrate that SMCP is a sperm autoantigen, recognized following vasectomy, and an isoantigen, recognized by antibodies generated through isologous immunization with sperm.