(HOMOGRAFTS IN THYMECTOMIZED, IRRADIATED MICE: RESPONSES TO PRIMARY AND SECONDARY SKIN GRAFTS.)

Adult thymectomized, irradiated mice restored with syngeneic bone marrow exhibit an accelerated response toward second-set skin homografts, although the response to the primary grafts is impaired. Such mice have a long-lasting impairment (up to 223 days) of the primary response to allogeneic grafts (but not to xenogeneic grafts) and show the greatest deficiency of response toward grafts sharing the same H2 locus as the host. Thymectomy in the adult mouse is ineffective in altering a state of homograft sensitivity induced prior to irradiation.