Figure 5.

Immunoglobulin-like transcript-2 (CD85j/ILT2) expression exerts little inhibitory effect on the cytotoxic function of CD8 T cells. (a) A human immunodeficiency virus (HIV) gag-specific CD8 T-cell clone showed, at most, a minimal inhibitory effect of ILT2 engagement on specific cytotoxicity. Cytotoxicity may be minimally enhanced in the presence of anti-ILT2 blocking antibody (◊) compared with isotype-control antibody (•), or no antibody (□), against gag peptide-armed targets. In the absence of peptide there is no killing (Δ). ILT2 blocking has no effect at all in specific lysis by three other antigen-specific T-cell lines (data not shown). (b) Blocking ILT2 also has no effect on specific lysis at limiting concentrations of peptide antigen. Effector cells, pretreated with blocking antibody (◊), control antibody (•), or no antibody (□), were tested for lysis of autologous B-LCLs treated with the indicated concentrations of cytomegalovirus (CMV) A0201-resticted peptide. (c) Freshly isolated peripheral blood mononuclear cells (PBMCs), stained for CMV A0201 peptide and selected for tetramer-positive CD8 T cells, were incubated with ILT2 or control antibody and used as effector cells. Blocking ILT2 increased the killing somewhat by one cell line, but not by another (data not shown). Preincunbation was performed in the presence of: (◊), blocking antibody; (•), control antibody; (□), no antibody.