The lymphocyte mediators of delayed hypersensitivity: the early phase cells.

Inbred rats were immunized with living BCG and lymphocytes which mediate tuberculin DTH and anti-tuberculosis immunity were found 10 days later in the draining lymph nodes, thoracic duct, blood, spleen and acute peritoneal exudates. The lymphocytes that mediated DTH incorporated 3HT in vitro, were large in size, sensitive to vinblastine but relatively resistant to irradiation, and had a short effective lifespan in syngeneic recipients. These properties characterize the cells as short-lived, nonrecirculating immunoblasts. In some experimental situations it was possible to dissociate the expression of DTH and immunity following the transfer of sensitized lymphocytes.