Factors influencing the vaccinia-specific cytotoxic response of thymocytes from normal and chimeric mice

Abstract

Following adoptive transfer into irradiated recipients, thymocytes can be induced to respond strongly to vaccinia virus. High levels of cytotoxic T-lymphocyte (CTL) activity may be generated from thymus, but not from spleen, of 3-day-old mice. The capacity of thymocytes to differentiate into effector CTL tends to be lost with age. Some of this loss may reflect positive suppression: a single, low dose of cyclophosphamide allows the reemergence of responsiveness in at least one mouse strain. Thymocytes from [A→(A x B)F1] and [(A x B)F1→A] chimeras show the response patterns that would be predicted from previous studies of lymph node and spleen cells. However, thymic function seems to be rapidl..