Serological Inhibition of Blast Transformation to Purified Streptococcal Antigens by Planned Immunization in HLA (A, B) Compatible Unrelated Individuals

Abstract

Sera obtained from planned immunizations between unrelated donors and recipients, identical or compatible at HLA-A and B, were assessed for their capacity to alter the in vitro response of a test panel of lymphocytes to PHA [phytohemagglutinin] and a purified streptococcal antigen (PSA). In the case of PHA, no serum effects were apparent. The response to PSA was significantly inhibited by 2 sera. When tested for their complement-dependent cytotoxicity on enriched populations of T [thymus-derived] and B [bone marrow-derived] lymphocytes, none of the sera manifested cytotoxicity against T cells nor did serological inhibition correlate with the capacity to lyse B cells. Inhibition of the PSA response is apparently mediated by blocking antibodies specific for a subset of lymphocytes, possibly T cells. While the precise mechanism governing the response to PSA is not known, an HLA-linked Ir [immune response] gene, expressed on a subset of T lymphocytes, may control immune responsiveness to PSA.