Mixed Antiglobulin Reaction (MAR)
Definition - What does Mixed Antiglobulin Reaction (MAR) mean?
Mixed antiglobulin reaction (MAR) is a test used to detect the presence of antisperm antibodies (ASA) on sperm. ASA identify sperm as being foreign attackers such as a bacteria or virus and start attacking them. These antibodies, thus, impair the fertility potential.
FertilitySmarts explains Mixed Antiglobulin Reaction (MAR)
There are two ways of detecting ASA through the MAR test:
- Direct MAR: in which antibodies present in the semen are tested
- Indirect MAR: which detects antibodies present in the serum (serum is blood from which clotting factors have been removed)
The direct MAR test involves mixing fresh, untreated semen with latex particles coated with human antibody (immunoglobulin/Ig) called IgG. Another antibody to IgG, called anti-IgG is then added to the mixture of fresh, untreated sperm and latex beads. These antibody-coated particles will recognize and attach to the region of the sperms wherever the antisperm antibodies (of the IgG type) are located.
The indirect MAR is done by adding washed motile sperm from a donor (screened to be free of antibodies) to the patient’s diluted serum. The mixture is incubated at 37°C for an hour. Then a drop of this mixture is processed as in a regular MAR test by mixing it with coated latex particles and anti-IgG. After 2 to 3 minutes, the percentage of motile sperms that bind to the antibodies (IgG) is recorded. The results are interpreted as follows:
- The test is considered negative: if the percentage of sperms that bind to the antibody mixture is less than 10%
- The test is interpreted as weakly positive: if 10-39% of motile sperms are covered by latex particles
- A value of 40% or greater is likely to impact fertility and is regarded as being positive
- The MAR test is considered strongly positive if >90% of motile sperms are incorporated into the mixture.
The MAR test is convenient, quicker, and requires less volume of ejaculate. The indirect MAR test is more sensitive (yields fewer false-positives) and accurate, hence, appears to be an ideal procedure to screen for sperm antibodies in serum.