Binding of the antigen L glutamic acid⁶⁰ L alanine³⁰ L tyrosine¹⁰ (GAT) by thymocytes from genetic responder and nonresponder strains of mice

The binding of ¹²⁵I GAT by purified murine thymocytes was studied by autoradiography. Antigen binding was found to be highly temperature dependent. Significantly more thymocytes bound GAT at 37° than at 4°; GAT bound at 37° was usually distributed in a 'cap' over one pole of the cell. Binding of GAT was specific, in that it could be inhibited by an excess of unlabeled GAT, but not by unrelated proteins. The immune response to GAT is under the control of an H 2 linked immune response gene; under most conditions nonresponder mice fail to develop effective T cell helper function necessary for a humoral immune response to GAT. However, both responders and nonresponders had similar numbers of thymocytes capable of binding GAT, indicating that T cells from nonresponding mice do possess a recognition mechanism for GAT. A relationship was found between the thymocyte receptor for GAT and the products coded for by the H 2 complex. The number of thymocytes binding GAT was reduced by 56 to 96% by preincubation with congenic anti H 2 sera. In contrast, anti Thy 1 and a number of anti immunoglobulin antisera failed to inhibit binding.