Some Cell Surface Properties of Thymus-Derived Lymphocytes in Bursectomized Chickens

Abstract

Delayed hypersensitivity reactions have been shown to be mediated by thymus-derived T lymphocytes (1,2). It is apparent from the specificity of delayed reactions and from the demonstration of T cell memory (3), that at some stage of differentiation, such cells are capable of recognizing specific antigenic determinants. It has been proposed that as in the case of B cells, the antigen recognition T cell is dependent on a surface immunoglobulin (Ig), the only molecule thus far identified with antigen combining sites (4). Experimental evidence of the presence of such Ig molecules on the T cell surface has been conflicting. Both positive and negative results have been obtained in 1) attempts to radioiodinate directly any surface Ig present on mouse thymocytes (5,6); 2) antigen binding studies (7,8); and 3) inhibition of T lymphocyte function with anti-Ig antisera (9,10). Since the agammaglobulinemic (aγ) chicken can be immunized to give a normal delayed hypersensitivity (DH) reaction, it provides an ideal system in which to study the nature of possible antigen receptor sites in a presumably sensitized population of T cells.