Bovine lineage-specific gamma delta (γδ) T cell GD3.5 antibody cross-reacts with cell surface antigens on ovine and caprine lymphocytes

A specifically defined function for γδ T cells is still a topic of intense debate. Thus, there is great importance in the identification of lineage-specific markers that characterize these cells. Early studies describe a family of lineage-specific cell-surface molecules on ruminant γδ T cells called WC1. More recently, a 220–240 kDa lineage-specific bovine γδ T cell surface marker, GD3.5Ag, was reported. Here, we used anti-bovine GD3.5Ab to study its cross-reactivity with caprine and ovine lymphocytes. Flow cytometric analysis demonstrated that GD3.5Ab binds ovine and caprine lymphocytes. In addition, immunoprecipitation experiments with GD3.5Ab demonstrate an ovine and caprine cross-reactive antigen that is similar in size to the bovine antigen. These results suggest that GD3.5Ag is well conserved among ruminant species and GD3.5Ag may play an important role in γδ T cell biology.