Rejection of a Transplantable Marek's Disease Lymphoma in Normal Versus Immunologically Deficient Chickens 2 3

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Abstract
Normal and immunosuppressed N-line chickens were challenged at 7 days of age with a transplantable Marek's disease (MD) lymphoma. They were subjected to immunosuppressive treatments that included embryonal bursectomy (BX), neonatal thymectomy (TX), cyclophosphamide (CY) administration, a combination of BX and TX or TX and CY administration, or neonatal infection with virulent MD virus. The transplant cells were of N-line origin. In all normal intact chicks, progressively growing palpable tumors at the inoculation site appeared, usually by 6-8 days; these regressed in most birds between 14 and 18 days post inoculation. Many birds in which transplanted tumors regressed later developed visceral lymphomas. Transplanted tumor grow1h and rejection were unaffected by TX or CY treatments, but the combined TX and CY treatment and prior MD virus infection significantly delayed tumor rejection. Bursectomized chicks developed fewer palpable tumors and, when they developed tumors, those tumors regressed more rapidly than did those in intact birds. Both BX and CY treatments markedly reduced the incidence of MD through 10 weeks. The enhanced transplant rejection in bursectomlzed chicks could have been due to “blocking antibody,” but the rejection pattern was not altered by repeated injections of sera from chicks with tumors or from chicks with tumors that regressed. injections of convalescent sera from MD virus-exposed birds enhanced the rejection of transplants in intact birds.