Effects of human thymic epithelial-conditioned medium on mitogen responsiveness of human and mouse lymphocytes

Abstract

The conditioned media from a variety of human tissue cultures, thymus, HeLa cells, labial epithelium, salivary glands, and fibroblasts, were examined for their effect on the response of human and mouse lymphocytes to mitogens. Conditioned media from thymus epithelial cultures (HTECM), but not from nonthymic epithelial cultures and fibroblasts, increased [3H]TdR incorporation into Con A- and PHA-stimulated thymocytes of man and mouse. No effect was seen on B lymphocytes. Target cells for HTECM were not found in human peripheral blood lymphocytes. In the mouse target cells were found in two thymocyte subpopulations, the cortisone-resistant and cortisone-sensitive, and in the spleen. Lymph node cells contained no target cells.