CTL adhesion and antigen recognition are discrete steps in the XXXX CTL-target cell interaction.

@entity1 @entity3138 @entity7937 @entity1453 @entity460
Th initial step in cytolytic T lymphocyte (CTL)-mediated cytolysis involves target cell adhesion and antigen recognition. To investigate these initial events in the CTL-target interaction, we used HLA-A2- and HLA-B7-specific @entity1 CTL clones and HLA-typed B lymphoblastoid target cells. By using two different adhesion assays, we demonstrated antigen nonspecific CTL-target cell adhesion. To more precisely define the contribution of the antigen-specific receptor to CTL-target cell adhesion, we used the HLA-A2, HLA-B7, and mock transfected RD target cells. Consistent with the results when using B lymphoblastoid target cells, the CTL clones demonstrated equivalent adhesions to the RD target cells whether or not they expressed HLA-A2 or HLA-B7. These results suggested that CTL-target cell adhesion occurred independent of the T cell receptor. By using the @entity460 -sensitive dye Indo-1 and flow cytometry, we assessed CTL-target cell adhesion and CTL activation. Simultaneous measurement of adhesion and intracellular free @entity460 demonstrated that CTL-target cell adhesion alone did not activate CTL clones. Both CTL-target cell adhesion and the presence of the appropriate HLA target molecule were necessary for the efficient activation of @entity1 CTL. MAb inhibition studies indicated that antigen nonspecific adhesion is largely regulated by the @entity1453 , @entity3138 ( @entity3138 / @entity3138 ), and @entity7937 cell surface molecules. These antigen nonspecific cell-cell interaction molecules appear to play an important role in facilitating antigen recognition and subsequent target cell lysis.
