Frequency and Restriction of Cytotoxic T Lymphocyte Precursors in Neonatally Thymectomized Mice

Abstract

Neonatal thymectomy causes a severe and definitive impairment of all T-cell functions (1). This fact has been considered for a long time as an indication that T-lymphocytes migrate obligatorily through the thymus, and that competent effector cells appear in the peripheral organs following a delay after birth. However, we have recently shown the presence, in the spleen of neonatally thymectomized (N-Tx) mice, of competent cytotoxic T lymphocyte precursors (CTL-P) (2). These CTL-P can be specifically activated in vitro upon antigenic stimulation in the presence of supernatants from Con A activated cells (Con A sup) or of a thymic humoral factor (THF). In this report, we provide further information about this pool of CTL-P. We have estimated their frequency and their degree of H-2 restriction in comparison with CTL-P which have differentiated under normal thymic influence.