CHARACTERIZATION OF NEW MONOCLONAL-ANTIBODIES IDENTIFYING AVIAN T-LYMPHOCYTE ANTIGENS

Six monoclonal antibodies (mAb) were produced to identify and characte rize surface antigens of chicken T cells. Determination of their react ivity with different lymphatic cells using immunofluorescence analysis demonstrates that mAb KH8, NA6, PD4 and TH8 stained 32-43 % blood lym phocytes, 72-77 % thymocytes and 19-27 % spleen cells, mAb OC5 approxi mately 99 % thymocytes and 55 % blood and spleen lymphocytes each, and mAb OC2 36 % blood lymphocytes, 79 % thymocytes and 62 % spleen cells . The KHS, NA6, PD4 and TH8 antibodies immunoprecipitated from lysates of surface-labeled chicken thymocytes a polypeptide of M(r) 60,000 un der non-reducing conditions and the OC5 antibody a glycoprotein of M(r ) 68,000 under reducing conditions. MAb OC2 precipitated a single poly peptide of M(r) 40,000 under both conditions. The mAb KH8, NA6, PD4, T H8 and OC2 inhibited Con A-induced proliferative responses of blood T cells in vitro. However, sepharose-bound or soluble OC5 antibody was a ble to increase DNA synthesis significantly. These results indicate th at (a) the mAb KH8, NA6, PD4 and TH8 identify the avian homologue of t he mammalian CD4 molecule, (b) the mAb OC2 detects the avian CD2 antig en, and (c) the mAb OC5 recognizes the putative avian CD5 homologue.