CELL-MEDIATED IMMUNE-RESPONSE INVITRO .1. DEVELOPMENT OF SUPPRESSOR CELLS AND CYTOTOXIC LYMPHOCYTES IN MIXED LYMPHOCYTE-CULTURES

Abstract

During the in vitro development of cytotoxic [mouse] lymphocytes (CL), suppressor cells also develop. Spleen cells or lymph node cells harvested from mixed lymphocyte cultures (MLC) on day 2 (day-2 MLC) and added to a fresh MLC suppressed the development of CL. This suppressive effect was sensitive to treatment with anti-.theta. and [rabbit] complement. The suppressive effect of day-2 MLC was not due to cytotoxic effects nor to altered kinetics of the development of CL. Thymidine hot pulse experiments showed that cell proliferation is necessary for the development of suppressor cells and CL. Although CL develop from hydrocortisone-treated spleen cells, day-2 MLC of hydrocortisone-treated spleen cells did not suppress the development of CL. Suppressor cells and CL are apparently derived from different thymus-derived cell subpopulations.