МАR-тест (антитела Ig А на поверхности сперматозоидов)

The MAR test (mixed antiglobulin/agglutination reaction) assesses sperm-bound antisperm antibodies of the IgA and IgG classes in native semen. MAR testing supports the evaluation of male infertility, with emphasis on suspected immune-mediated (immunologic) infertility. Used together with standard semen analysis, the assay reports the proportion of morphologically normal, motile sperm coated with IgA and/or IgG. A higher percentage of antibody-coated motile sperm indicates an immune factor that may contribute to reduced fertilizing capacity and guides subsequent andrology assessment.

Antisperm antibodies (ASA) are immunoglobulins directed against surface or structural antigens on spermatozoa. In healthy males, the blood–testis barrier and immune tolerance protect sperm antigens from immune recognition. Breach of this barrier can trigger autoimmunity with formation of ASA. Reported triggers include bacterial or viral infections, testicular cancer, varicocele, cryptorchidism, trauma, and prior surgery. ASA may arise within the testes and epididymides or along the vas deferens, and they can target antigens on the head, midpiece, tail, or multiple sperm regions. ASA implicated in immunologic infertility are primarily of the IgA and IgG isotypes. IgM is rarely detected in semen due to its large molecular size and is not routinely measured. IgA is produced locally and acts at mucosal surfaces; detection of abundant IgA on sperm supports disruption of the blood–testis barrier. IgG typically enters semen from the circulation when the barrier is compromised and may persist for extended periods. The MAR (mixed antiglobulin) test evaluates native ejaculate by mixing sperm with latex particles or erythrocytes coated with human IgA and IgG reagents and then adding monospecific anti–human IgG antiserum. Formation of mixed agglutinates indicates sperm coated with IgA and/or IgG on their surface. Per World Health Organization guidance, MAR testing is performed only in conjunction with a complete semen analysis, and it should be undertaken when sperm concentration and motility are adequate. The readout is the percentage of morphologically normal, motile sperm bound by reagent particles; results are considered consistent with immunologic infertility only when particles attach to at least 50% of normal motile sperm. Sperm that are otherwise morphologically and functionally normal but coated with ASA may fail to participate in fertilization and account for infertility. Testing is not feasible when no motile sperm are present, and interpretation should be integrated with clinical history and other diagnostic findings.