Purification and Biochemical Analysis of Antigen-Specific Suppressor Factors Isolated from T-Cell Hybridomas

Abstract

Recent advances in technology have made the understanding of the molecular and biochemical aspects of immune regulation an attainable goal. We have used some of these advances in somatic cell hybridization, microanalytical peptide chemistry and recombinant DNA technology, to study the molecular aspects of antigen-specific suppression of immune responses. These studies have used a group of related polypeptide antigens; L-glutamic acid⁶⁰-L-alanine³⁰-L-tyrosine¹⁰ (GAT), L-glutamic acid⁵⁰-L-tyrosine⁵⁰ (GT), and L-glutamic acid⁵⁰-L-alanine⁵⁰ (GA). The immune responses in mice to these polymers are controlled by immune response (Ir) genes which map to discrete loci within the I region of the major histocompatability complex (H-2). In the case of GAT for example, immunization of mice bearing H-2^a,b,d,f,k haplotypes results in antibody production to GAT and primes lymph node T cells for subsequent in vitro proliferation in response to GAT. In mice bearing the H-2^p,q,s haplotypes immunization with GAT neither stimulates antibody-forming cells nor does it prime lymph node T cells for proliferation unless the GAT is complexed with an immunogenic carrier such as MBSA. Earlier studies suggested that the reason for this lack of responsiveness in mice bearing H-2^p,q,s haplotypes was the development of GAT-specific suppressor T cells (1–5). More recently it has been shown that extracts from GAT-specific suppressor T cells from non-responder mice contain soluble proteins which can specifically suppress the response to GAT. These soluble proteins are called GAT-specific suppressor T-cell factors (GAT-TsF) and may also be found in the supernatant of cultures or cell extracts from responder mouse strains exposed to GAT under the appropriate conditions (6,7).