Human T lymphocyte clones reactive in primed lymphocyte typing and cytotoxicity

Abstract

The human HLA-D region, the presumed evolutionary homologue of the H–2 I region in mouse and similar genetic regions in other species¹, codes for multiple antigenic determinants, a finding consistent with the existence of multiple loci^2,3. One method developed to define D region encoded determinants is primed LD typing (PLT) wherein cells of one individual are primed in vitro in a mixed leukocyte culture (MLC) to allogeneic HLA-D encoded determinants associated with one haplotype^4,5. The PLT cells give a rapid proliferative response when restimulated in secondary culture with either the priming cells or third party cells that carry the priming antigen(s). However, as in many cases a PLT cell is probably primed to several determinants, different restimulating cells from unrelated individuals will engender a range of responses varying from very high to very low, presumably depending on the number of determinants shared (or cross-reactive) between the priming and restimulating cells. Such results are difficult to interpret in terms of defining antigenic determinants on the cells of various individuals. Fathman and Hengartner⁶ have circumvented this problem in mouse by cloning murine T lymphocytes from multiply restimulated PLT cells; the progeny of any one clone give highly specific proliferative responses. We report here the use of the supernatant of phytohaemagglutinin (PHA)-stimulated mixtures of human allogeneic cells^7,8 (designated T-cell growth factor or TCGF) to grow ‘clones’ of human T lymphocytes following alloactivation in MLC. Clones that give PLT-type responses do so in a highly antigen-specific manner. Following cloning, cells in many cases have undergone 25 or more divisions, thus yielding in excess of 1×10⁸ progeny.