HLA class l specific t lymphocyte clones with dual alloreactive functions

Four human T lymphocyte clones exhibiting proliferative responses to class I HLA antigens were isolated from an in vitro mixed lymphocyte culture (MLC). Three clones expressed the Leu-2⁺3^– phenotype and demonstrated proliferation in response to HLA-B8, while the fourth clone expressed the Leu-2^–3⁺ phenotype and proliferated in response to HLA-A2. These clones were also cytotoxic towards cells bearing the same target antigens. Blocking studies utilizing monoclonal antibodies demonstrated that proliferation was triggered by determinants on the class I molecule itself, and these determinants appear to be spatially close to those which determine serologic allospecificity. These findings support the concept that the class I molecules themselves are the weak MLC stimulating determinants previously mapped to the HLA-A and B regions of the major histocompatibility complex.Abbreviations used in this paper B-LCL B-lymphoblastoid cell line - cpm counts per minute - FCS fetal calf serum - HS human serum - ³H-TdR tritiated thymidine - IL-2 interleukin-2 - IL2-CM interleukin-2 containing conditioned medium - MHC major histocompatibility complex - MLC mixed lymphocyte culture - MoAb monoclonal antibody - PBL peripheral blood mononuclear leukocytes - PLT primed lymphocyte test