Generation of targets for alloreactive CTL using purified H-2K k in liposomes and polyethylene glycol

Abstract

The ability of a purified major histocompatibility antigen to serve as the target cell antigen for alloreactive CTL (H-2 d anti-H-2 k) was examined. Tumor cells syngeneic with responding CTL were used as targets following modification with purified alloantigen (H-2K k). A short incubation of tumor cells with H-2K k liposomes followed by the addition of polyethylene glycol (PEG) yielded modified tumor cells that were recognized and lysed by CTL. The macrophage-like cell line P388D1 was readily recognized following liposome and PEG modification; apparently because these cells can withstand PEG mediated insertion of H-2K k and lipid into their membrane. The generation of targets by PEG mediated modification was most efficient using liposomes prepared with an H-2K k:lipid ratio of about 1:500. H-2K k containing liposomes prepared with negatively charged phospholipids readily attached to P388D1 cells, however these cells were not targets for CTL unless PEG was added. The specificity of CTL recognition and lysis of liposome modified cells was shown by the reactivity of CTL primed against alloantigens other than H-2K k and by antibody (anti-H-2K k) blocking of recognition and lysis. These results demonstrate that purified H-2K k can serve as the alloantigen for CTL lysis and suggest that the H-2 must be oriented in the target cell lipid bilayer to serve as the alloantigen for CTL mediated target cell lysis.