HOMOTYPIC AGGREGATION OF OVINE LEUKOCYTE INDUCED BY ANTI-LEUCOSIALIN (CD43) MONOCLONAL-ANTIBODIES

Four monoclonal antibodies directed against ovine/bovine leucocyte ant igens (Co.44B8, Co.11F10, Co.33B3 and Co.26F4) were produced and all r ecognized an antigen with an apparent molecular weight of 105 kDa unde r reducing conditions. This molecule was considered to be the ovine/bo vine analogue of human, rat and mouse CD43 or leucosialin. This conclu sion was based on (a) the cellular distribution of the antigen which w as similar to that described in other species, (b) a decrease of appar ent M(r) (150 kDa) after treatment with neuraminidase, and (c) product ion of cell aggregation by the four monoclonal antibodies and the infl uence of temperature and metabolic inhibitors on this phenomenon. Co.4 4B8, Co.11F10, Co.33B3 and Co.26F4 all recognized and immunoprecipitat ed the molecule after neuraminidase treatment of the cells. The data i ndicate an important function of CD43 as a mediator of cell aggregatio n for ruminant cells.