Lymphocytes from thymectomized rats: immunologic, proliferative, and metabolic properties.

Thoracic duct lymphocytes from neonatally thymectomized Lewis rats fail to produce runt disease in newborn Brown Norway rats when injected with up to ten times the number of normal lymphocytes needed to cause runting. The immunologically deficient lymphocytes appear, however, to confer tolerance, and at least some enlarge and divide when stimulated in vitro with phytohemagglutinin, or xenogeneic or allogeneic cells. Small lymphocytes from thymectomized animals have defective RNA metabolism as judged by a marked impairment in their ability to incorporate uridine-5-H(3) or cytidine-H(3) in vitro.