Differential expression of two t cell receptors, tcr1 and tcr2, on chicken lymphocytes

Abstract

A monoclonal antibody, TcR2, has been shown to recognize an avian homologue of the mammalian α/β T cell receptor (TcR). The TcR2‐reactive molecule was found to be a T3‐associated heterodimer with relative molecular mass of 90‐kDa consisting of disulfide‐linked 50‐kDa and 40‐kDa polypeptides. The sizes of the deglycosylated TcR2 polypeptides differed from those of TcR1, an avian homologue of the mammalian γ/δ T cell receptor. Immunofluorescence analysis revealed that TcR1 and TcR2 are expressed on separate populations of T cells during their development first in the thymus and then in the periphery. Ontogenetic studies revealed that the TcR1+ thymocytes are generated first and the generation of TcR2+ cells begins approximately 3 days later. While most TcR2+ cells in the thymus expressed both CT4 and CT8, TcR2+ cells in blood and the spleen were either CT4+ or CT8+. The TcR1+ cells in blood and thymus were CT4−CT8−, but the majority of TcR1+ cells in the spleen surprisingly expressed the CT8 marker. The data suggest that TcR1 and TcR2 cells are generated in the thymus as separate T cell sublineages.