Transplantable Marek's disease lymphomas. I. Growth characteristics during development in two inbred lines of chickens.

Lymphomas developed in the pectoral muscle of most chickens inoculated with cells from primary Marek's disease virus-induced visceral tumors obtained from chickens of the same inbred line. However, serial passaging of the lymphoma cells in histocompatible hosts generally resulted either in an eventual absence of tumor formation at the inoculation site or in tumor regression. Exceptions occurred in two experiments, where tumors grew rapidly and the hosts died early. Subsequent passaging of cells from these tumors into syngeneic recipients resulted in the development of two new transplantable Marek's disease (MD) lymphomas. These lymphomas, which were developed in chickens of related inbred lines--G-B1 and G-B2--were designated MDCT-UG1 and MDCT-UG2, respectively. Cells from the transplantable lymphomas possess different major histocompatibility complex (MHC) antigens, since G-B1 and G-B2 chickens have different MHC genotypes. A change in the cellular composition during a particular passage for both lymphomas, as indicated by marked increases in the percentage of cells possessing a MD tumor-associated surface antigen (MATSA), suggests that each arose as a result of the emergence and selection of a highly malignant clone of cells.