Functional subclasses of T lymphocytes bearing different Ly antigens. II. Cooperation between subclasses of Ly+ cells in the generation of killer activity

Abstract

Lymphocytes from BALB/c or C57B6/6 mice that develop killer activity to alloantigens belong to the numerically small Ly 23 subclass of peripheral T cells, distinguished by selective expression of Ly 23 determinants on their surfaces. The maturation of these cells to killer cells can be amplified by Ly 1+ cells, which do not themselves contribute to the killer cell pool. This amplification was abolished by excluding Ia('Beta')+ cells from the stimulator population during mixed lymphocyte culture (MLC), suggesting that amplification is due to selective recognition of I region antigens by Ly 1+ cells, a conclusion already drawn from previous evidence that Ia differences activate Ly 1+ cells but not Ly 23+ cells. These and other experiments indicate that amplification of killer cell production in vitro by Ly 1+ cells is not due to their conversion to Ly 23+ cells during MLC, but to their ability to recognize major histocompatibility complex determinants not recognized by Ly 23+ cells.