ANALYSIS OF MONOCLONAL-ANTIBODIES SPECIFIC FOR THE GAMMA-DELTA TCR

gamma delta T cells in ruminants can be subdivided in two or more subp opulations on the basis of the expression of surface antigen WC1, whic h can exist in different isoforms. In this study, 18 monoclonal antibo dies (mAbs) submitted to the Third International Workshop that were pr edicted to react with gamma delta TcR molecules were analysed and expr ession of their antigens was investigated on the different gamma delta T cell subpopulations. A set of control mAbs positive for TcR1 (86D), BoCD3 (MM1A), WC1 (B7A1, BAQ4A, CACTB32A, and BAQ89A) was included fo r comparative studies, Previous investigations demonstrated eight of t he mAbs immunoprecipitated peptides with apparent M(Gamma)s of 37 and/ or 47 kDa, indicating they recognized determinants on the T cell recep tor, TcR1. Two color flow cytometric analyses in the present study dem onstrated the mAbs formed three groups; group 1, a set of mAbs that re cognize TcR1 determinants expressed on all gamma delta T cells and gro ups 2 and 3, sets of mAbs that recognize TcR1 determinants on some gam ma delta T cells: TcR1-N6 and TcR1-N7 respectively, mAbs from the latt er groups define families of TcR1 molecules that express either one or both of the determinants. These antigenically distinct forms of TcR1 are expressed in equal proportion on the two gamma delta T cell popula tionss that express one of the mutually exclusive isoforms of WC1, WC1 -N3 and WC1-N4. The data indicate usage of the mAb-defined families of the gamma delta TcR is primarily restricted to the WC1(+) subpopulati on of gamma delta T cells. However, a small subpopulation of CD2(+), W C1(-) gamma delta T cells expresses a form of TcR1 positive for the de terminant TcR1-N6.