Antisperm

Antisperm refers to antibodies directed against sperm antigens, most commonly termed antisperm antibodies (ASA). These antibodies can be present in men or women and may interfere with normal fertilization by binding to sperm and altering its function or movement.

Mechanism and impact on fertility. Antisperm antibodies can attach to various parts of the sperm, such as the head or tail. This binding can cause agglutination (clumping), immobilization, or reduced motility, and can interfere with important processes like capacitation and the acrosome reaction. Antibody binding can also hinder sperm binding to the cervical mucus, zona pellucida, or oocyte, thereby reducing the probability of fertilization. The effect depends on antibody type (IgG, IgA, IgM), the targeted sperm antigen, and the site of antibody interaction. Antisperm antibodies may be found in seminal plasma, serum, or both, and can arise after testicular injury, infection, surgery (including vasectomy or reversal), or abnormal exposure to sperm antigens.

Diagnosis. Detection of antisperm antibodies is typically pursued in the evaluation of unexplained infertility or recurrent pregnancy loss. Common tests include the mixed antiglobulin reaction (MAR) test, the immunobead test (IBT), and related assays that assess the ability of antibodies in serum or semen to bind to sperm. Positive results may be reported as titres or qualitative findings, and results are interpreted alongside semen analysis and clinical history.

Management and prognosis. Treatment depends on fertility goals and test results. For many couples, assisted reproductive technologies such as intracytoplasmic sperm injection (ICSI) can bypass some antibody-related barriers. Sperm washing or selection techniques may be used in some scenarios. Immunosuppressive therapy is not routinely recommended due to limited evidence and potential risks. Addressing underlying infections or inflammation may help in some cases. Natural conception is less likely when significant antisperm antibody activity is present, but outcomes with ART are variable and can be successful.