SURFACE-ANTIGENS OF LITOMOSOIDES-CARINII-MICROFILARIAE - AGGLUTINATING ANTIBODIES REACT WITH SHEATH COMPONENTS OF 40-KILODALTON AND 120-KILODALTON MOLECULAR-MASS

This study was conducted to identify surface antigens of the microfila rial sheath of Litomosoides carinii which are accessible to antibodies . Rabbit antisera were raised against the soluble and insoluble fracti ons of purified sheaths by extracting them with a buffer containing 2- mercaptoethanol and sodium dodecylsulphate. These sera and rabbit hype rimmune sera directed against homogenates of total microfilariae, matu re (i.e. microfilariae liberating) female parasites and excretory-secr etory products of adult females were able to agglutinate live and form aldehyde-fixed microfilariae. When the antisera directed against sheat h constituents were administered to patently infected Mastomys concha, the microfilaraemia of these animals was rapidly reduced and remained low for a period of 2-3 weeks. Antibodies specifically binding to the microfilarial surface were immunoaffinity-purified on formaldehyde-fi xed microfilariae. The antibodies react with sheath antigens of 40 and 120 kDa molecular mass which are produced by the epithelium of the di stal uterus of the mature female, secreted and attached to the surface of the sheaths. A 120 kDa antigen recognized by anti-sheath surface a ntibodies was also detected in the excretory-secretory products of in vitro-cultured immature female L. carinii from day 30 post-infection o nwards. In the excretory-secretory products of mature adult female par asites recovered on day 130 post-infection, this 120 kDa molecule was absent. However, material reacting with the antibody was detected in t he stacking gel of SDS-polyacrylamide gels. This finding may indicate that the basic units forming the 120 kDa antigen of immature adults or microfilarial sheath surface antigens occur in a highly polymerized f orm in the excretory-secretory products of mature female parasites.