Monoclonal antibody to Lyt 2 antigen blocks H–2I- and H–2K- specific mouse cytotoxic T cells

Abstract

It has been proposed that the murine cell surface antigen Lyt 2 could serve to distinguish cytotoxic T lymphocytes (CTLs) and their immediate precursors, which bear Lyt 2, from helper T cells, which do not¹. Later work, however, has demonstrated that Lyt 2⁺ cells can ‘help’ B cells mature into antibody-secreting cells, provided that the B cells differ from the allo-helper T cells at the K or D region of the H–2 major histocompatibility complex (MHC)². Furthermore, a T-cell line has recently been described which is Lyt 2⁻ but specifically cytotoxic for H–2I region determinants^3,4. These new findings have prompted an alternative hypothesis, that Lyt 2 antigen does not discriminate between cytotoxic and non-cytotoxic (helper) T cells, but rather between I-region- and K/D-region-specific cells⁵. In this new view, the apparent association between presence of Lyt 2 antigen and killer T-cell function merely reflects the tendency, by no means absolute^6–8, for CTLs to recognize K- or D- rather than I-region determinants⁹. We show here that I-region-specific murine CTLs, generated in primary in vitro culture, do in fact bear the Lyt 2 antigen, as do CTLs directed against the K region of H–2.