The long-term goal of this project is to understand how B cells and T cells interact in order to regulate an immune response. Using recombinant DNA techniques, we will isolate genes encoding antigen receptors from B cells and several subsets of T cells, all of which recognize the same antigen, the synthetic polypeptide, GAT. Several classes of GAT-specific lymphocytes have been cloned; they can be manipulated both in vivo and in vitro. These include: B cells, helper T (TH) cells and 3 subsets of suppressor T (Ts) cells. The B cell response to GAT is quite restricted in diversity. The receptor genes from GAT-TH cells are being characterized using T cell receptor (TcR) probes; we will determine whether there is a bias in the T cell repertoire for GAT, analogues to the B cell response to this antigen. Additionally, we have shown that some Ts cells transcribe TcR genes; we will characterize the organization, expression, and functional potential of TcR alpha, beta, and gamma genes in Ts cells. However, many Ts cells do not seem to use the beta chain of the TcR. We will clone the receptor genes from these cells by screening cDNA libraries with three different probes: 1) oligonucleotide probes predicted from protein sequences obtained for the antigen-binding factors secreted by Ts cells; 2) serological reagents directed against the I-J, Tsu/Tind, and idiotypic determinants on Ts cells and their factors; and 3) subtractive probes enriched for Ts transcripts. The receptor genes used by Ts cell have never been cloned; they will be mapped, characterized, and compared to the receptors used by TH and B cells specific for the same antigen. By comparing the genetic sequences used by the various lymphocyte classes to encode GAT-binding polypeptides, we will be in a unique position to study the molecular bases of antigen recognition and MHC restriction. Since the cells have been cloned, we will be able to determine the role of the receptors in immune cellular regulation and lymphocyte activation. A better understanding of the molecular controls operating in immune regulation is of primary importance in determining the basic mechanisms and defects in certain immune deficiency diseases and autoimmune disorders.