Sperm under siege: How anti-sperm antibodies impact fertility
Key Takeaways
The presence of anti-sperm antibodies (ASAs) may lead to immunological infertility. However, further research is required, despite the surrounding controversies.
Anti-fertility vaccines are successfully being used to reduce fertility rates in animals, and they have the potential for human use.
Exciting research on topical contraception using ASAs is underway and may offer contraception through passive immunity.
Infertility is a disease of the reproductive system which can occur due to both male and female factors, or a combination of both. Immune infertility induced by anti-sperm antibodies (ASAs) is one such cause of infertility.[]
Etiology of ASAs
In men, the etiology of ASAs is speculated to be a result of impairment in the blood-testis barrier because of trauma or infection. However, in many cases the exact cause is not known.
Vasectomy, varicoceles, cryptorchidism, inguinal hernias, auto-immune diseases, and viral and bacterial infections may all lead to the development of ASAs, but there is still a lot of speculation and need for further research.
Women can develop ASAs as well, through damage to the cervical mucosa or from oral or anal intercourse with deposition of sperm into the GI tract, according to researchers writing in Vaccines.[]
The mechanisms by which ASAs may lead to infertility include impaired sperm motility, impaired ability of the sperm to penetrate the cervical mucus, sperm agglutination, and impairment of the initial stages of embryo development. However, the causative mechanisms are still poorly understood and require further research.
Current controversy with ASAs
ASAs do not always cause infertility, and therefore the relationship between their presence and infertility is quite complex.
Sperm agglutination alone is not enough to diagnose immunological infertility, explain the authors of a review on ASA testing and male immunological infertility, but its presence may signify the existence of ASAs.[]
Furthermore, evidence to support the treatment of immunological infertility using steroids or intrauterine insemination is weak. This has created a wide range of protocols among physicians, with some clinics scrapping ASA testing in the preliminary phase of evaluation of male infertility, while others still use the testing routinely, offering treatment options that may not be based on proper evidence.
The many gaps in knowledge with regards to immunological infertility diagnosis and cause, as well as ASA screening and treatment, highlight the need for further research in this area.
Anti-fertility vaccines
As noted in the review article in Vaccines, the development of an anti-sperm vaccine for men is challenging due to the sheer number of spermatozoa present in the male reproductive tract.
The anti-sperm vaccines currently in development achieve their effect via IgA secretion in the prostate, which leads to the creation of antibodies in the male reproductive tract. At present, a number of anti-fertility vaccines are being used successfully to reduce fertility in animals.
Topical contraception using ASAs
A very interesting area of current research involving ASAs is that of contraception.[] Passive immunity by means of introducing antibodies to the vaginal canal is not a new concept and has been studied using HIV and HSV-2. However, the use of ASAs applied vaginally for contraception has only more recently been the subject of research.
Human contraception antibody (HCA) has been created using IgM anti-sperm mAb. The variable sequence of this antibody was combined with invariant IgG1 sequences to produce an IgG1 mAb. Preclinical testing of this antibody demonstrated sperm agglutination activity as well as sperm immobilization in the presence of complement, and a phase 1 clinical trial is currently underway.
What this means for you
As physicians, we are trained to follow evidence-based guidelines and practices. However, immunological infertility by means of ASAs is not clearly understood. The use of routine testing in the preliminary phase of male infertility may not be a scientifically sound choice, especially because the efficacy of treatment is unclear. Nonetheless, there may be instances where ASA testing is the logical next step. Research on anti-fertility vaccines and topical contraception using ASAs is ongoing, so it is important to stay up to date on current studies and practices in reproductive health.