CD27-CD27 LIGAND CD70 INTERACTIONS ENHANCE ALLOANTIGEN-INDUCED PROLIFERATION AND CYTOLYTIC ACTIVITY IN CD8(-LYMPHOCYTES() T)

To study the role of CD27-CD27 ligand (CD27L)/CD70 interactions in the generation of murine allospecific T cell responses, SF9 cells or cell membranes expressing recombinant human CD70 were added to in vitro ML C containing C57BL/6 (H-2(b)) responder cells and class I and II MHC d isparate H-2(b/d) stimulator cells. Alloantigen-specific CTL generatio n, CD8(+) T cell proliferation, and levels of N-alpha-benzlyloxycarbon yl-L-lysine thiobenzyl esterase activity were enhanced in the presence of human CD27L/CD70 expressed on SF9 cell membranes. Enhancement of C D8(+) T cell responses occurred in the absence of any discernible effe cts on CD4(+) T cell proliferation or IL-2 responses. Additional studi es demonstrated that CD27L/CD70-expressing membranes enhanced prolifer ative responses to class I MHC differences but had no effect on prolif erative responses to class II MHC disparities. Enhancement of allospec ific CTL generation was also observed when CD27L/CD70-expressing membr anes were added only during the last 24 to 48 h of 5-day MLC. Thus, th e present studies suggest that CD27-CD27L/CD70 interactions can select ively enhance differentiation of Ag-specific CD8(+) T cell effector me chanisms under conditions in which Th cell responses are not altered.