Q: What are antisperm antibodies and what do they do?

A: Antibodies are proteins, chemicals produced by the body's immune system to protect the body and help fight infections or other foreing substances.  

Antisperm antibodies are antibodies against sperms produced by men or women. There are three types of antisperm antibodies:

  1. Immunoglobulin G (IgG)
  2. Immunoglobulin  A (IgA)
  3. Immunoglobulin (antisperm antibody) M (IgM);

Each one of these is known as a specific immunoglobulin (antisperm antibody) isotype. The most common are IgG and IgA; the third, IgM, is mainly related to infections but still has the ability to destroy sperm and to make them agglutinate (stick together).

  • A woman can develop antibodies against sperm similar to an allergic reaction. These antibodies can negatively affect fertility.
  • A man can produce sperm antibodies against his own sperm when his sperm are exposed to his immune system (the testicles normally keep sperm isolated from the rest of the body and its immune system). This can happen after damage to the testicles, surgical procedures (such as biopsy or vasectomy), and prostate gland infection.

 Antisperm antibodies can impair the normal fertilization process in many different ways:

  • A man's antibodies can interfere with sperm motility by immobilizing or agglutinating (sticking together) the sperm, or interfere with sperm-cervical mucus interaction and transport.
  • At the level of uterine or tubal fluids the antisperm antibodies can also interfere with penetration of the egg (oocyte), with sperm fertilization, and perhaps with zygote development by impairing early cleavage and by damaging the implantation process.

The present scientific literature is not completely clear whether antisperm antibodies are involved in pregnancy losses.