Quantitative studies on the precursors of cytotoxic lymphocytes. II. Specificity of precursors responsive to alloantigens and to concanavalin A.

A microculture system was used to examine the specificity of cytotoxic T lymphocytes (CL) derived from single precursors. Our data indicate that clones derived from single precursors of CL (CLP) are specific. Thus, RNC mice (H-2k) simultaneously stimulated by both H-2d and H-2b antigens produce clones which are specific for either H-2b or H-2d but not for both. In lymph node (LN), the frequency of CLP giving rise to clones specific for H-2d and H-2b is 1/480 and 1/860, respectively. Clonal specificity is also maintained when Con A is used to activate the precursors. With a nonspecific assay of CL, it was found that 2.5% of the cells in LN are stimulated by Con A to produce clones of CL. Among the CLP stimulated by Con A, 2.1% of the clones are specific for H-2d alloantigens. An unexpected finding was that 18% of the clones produced by Con A stimulation lysed EL4 tumor cells, which carry H-2b; however, only a small proportion of these clones were specific for the H-2b alloantigen. The antigen on EL4 which accounts for the high response has not been characterized.