PHYTOHEMAGGLUTININ REACTIVITY OF LYMPHOID CELLS IN AGING NEONATALLY THYMECTOMIZED RATS

Abstract

The impairment of phytohemagglutinin (PHA) responsiveness of lymphocytes derived from neonatally thymectomized rats under a few months of age was demonstrated previously. In the present study, it is shown that the lymphocytes of young thymectomized rats were unresponsive to PHA stimulation and that those derived from older neonatally thymectomized rats react more vigorously than lymphocytes of nonoperated controls. The spontaneous ³HTdR incorporation of lymphoid cells from 1-year-old neonatally thymectomized rats was also higher as compared to the control cultures. Moreover, immunization of thymectomized rats with Freund's adjuvant further increased the PHA responsiveness of their lymphocytes. Under discussion is whether a high PHA responsiveness of lymphocytes of aging neonatally thymectomized rats injected with Freund's adjuvant reflects a situation in which the loss of T and B cell cooperation leads to autoimmune reactions.