Equine leucocyte antigen system. III. Non-MHC linked alloantigenic system in horses.

A new, non-MHC linked alloantigenic membrane antigen on the equine lymphocytes is described. This antigen was characterized with alloantisera in the two-stage microcytotoxicity test and designated as ELy-1 antigen. The frequency of ELy-1 antigen positive animals in various populations is close to 50%. ELy-1 shows an autosomal, dominant inheritance. Since an allelic antigen (s) could not be demonstrated in family studies, it is assumed that only two alleles ELy-1+ and ELy-1- exist. The ELy-1 antigen in positive animals is expressed on both T and B lymphocytes but it is not present on erythrocytes and thrombocytes. The incidence of ELy-1 antigen positive animals is significantly higher in horse groups suffering from chronic bronchitis or from laminitis, compared to clinically healthy controls.