Anti sperm antibodies and the need for their assessment have been a source of great controversy. Normally sperm develops within the testes in the seminiferous tubules and are completely isolated from the man’s circulating blood (via a blood testes barrier). This blood testes barrier is important since sperm (with their unique surface antigens) elicit an immune response if detected by the immune cells in the man’s blood, and the antibodies that are formed against sperm are designed to immobilize and destroy them.
Anti sperm antibodies can theoretically cause infertility by interfering with the sperm’s ability to arrive at and to fertilize the egg. In tests that have specifically correlated the location of anti sperm antibodies on the sperm (head, midpiece, tail) and the demonstrated defect in fertility have reported that head directed antibodies affect binding of the sperm head to the egg while sperm tail directed antibodies affect sperm motility.
A number of events can disrupt the blood testes barrier and allow the immune system to become activated against the sperm. These include trauma to the testes, torsion (twisting) of the testes, a history of a vasectomy and reversal, any other surgery within the scrotum, and infection within the testes.
The postcoital test is the most widely used test for antisperm antibodies yet it is quite nonspecific. That is, abnormal postcoital test results may be due to antisperm antibodies or a large variety of other factors. It is widely accepted that a normal postcoital test result if properly timed to allow for activation of the immune system (here, the complement system) rules out significant motility abnormalities due to antisperm antibodies. There remains the possibility of head directed antibodies that may effect binding of the sperm to the egg, but the incidence of these as a cause for infertility is unestablished and generally considered low. Testing for these antisperm antibodies may have greater benefit if In Vitro Fertilization is performed.
The two recognized and widely accepted testes to specifically assess for the presence of antisperm antibodies are:
the SpermMar test: this is called a “mixed agglutination test” in which (a) antisera to a class of antibodies (IgG antibodies) is incubated with the sample being tested along with (b) known IgG type antibodies immobilized onto latex beads or red blood cells. In the presence of IgG antibodies adherent to the sample sperm (that is, antisperm antibodies), the anti-IgG antibodies in the test solution (which binds to more than one IgG antibody) binds the sperm to form a bridge to the immobilized test IgG antibodies. This will form large clumps (agglutinations) of sperm stuck to either latex particles or red blood cells, which can easily be seen under the microscope. The benefit of this test is that it is performed on unprepared (unwashed) semen so that it can be an office screening test. Interpretation of test results are not well established, with 10-39% of motile sperm attached to latex being considered significant,
greater than 40% bound being considered highly significant, and less than 10% bound being likely insignificant. The WHO (World Health Organization) uses 10% as the cutoff of normal.
the Immunobead test: this is a sophisticated test in which beads bound to antibodies specifically directed against either IgG, IgM or IgA types of antibodies are incubated with washed motile sperm. The test solution’s beads will bind to any sperm containing the specific antibodies detected by the beads. This test will further allow detection of the site on the sperm (head, tail, midpiece) containing the antibodies, resulting in the detection of say “IgG antibodies against the head of the sperm.” The WHO considers greater than 20% of sperm bound to immunobeads as abnormal. This test certainly provides a large amount of information concerning the type and location of the antisperm antibodies in the sperm sample tested. However, the importance of this amount of information is controversial.