γδ T cells in ruminants can be subdivided in two or more subpopulations on the basis of the expression of surface antigen WCl, which can exist in different isoforms. In this study, 1g monoclonal antibodies (mAbs) submitted to the Third International Workshop that were predicted to react with γδ TcR molecules were analyzed and expression of their antigens was investigated on the different γδ T cell subpopulations. A set of control mAbs positive for TcRl (86D), BoCD3 (MMIA), WCI (B7Al, BAQ4A, CACTB32A, and BAQS9A) was included for comparative studies. Previous investigations demonstrated eight of the mAbs immunoprecipitated peptides with apparent M,s of 37 and/or 47 kDa, indicating they recognized determinants on the T cell receptor, TcRl. Two color flow cytometric analyses in the present study demonstrated the mAbs formed three groups: group l, a set of mAbs that recognize TcRl determinants expressed on all γδ T cells and groups 2 and 3, sets of mAbs that recognize TcRl determinants on some γδ T cells: TcRl-N6 and TcRl-N7 respectively. mAbs from the latter groups define families of TcRl molecules that express either one or both of the determinants. These antigenically distinct forms of TcRl are expressed in equal proportion on the two γδ T cell populations that express one of the mutually exclusive isoforms of WCl, WCl-N3 and WC1-N4. The data indicate usage of the mAb defined families of the γδ TcR is primarily restricted to the WCl + subpopulation of γδ T cells. Moreover, a small subpopulation of CD2+, WCI- γδ T cells expresses a form of TcRl positive for the determinant TcRl-N6. |
