Virus-induced interferon production in canine lymphoid cell cultures

Virus-induced interferon (IFN) production in canine lymphoid cells was studied, using Newcastle disease virus as principal inducer. It was found that spleen cells at a concentration of 5 X 10(6) cells/ml with Newcastle disease virus at a multiplicity of infection of 1, incubated at 37 C in 5% CO2 for 24 hours, produced highest titers of IFN. Among the lymphoid cells from different tissues, IFN production was in the order of spleen = bone marrow greater than thymus greater than mesenteric lymph node greater than or equal to peripheral blood lymphocytes. Macrophages did not produce IFN, and virus-induced IFN production in spleen cells did not depend on the presence of phagocytic mononuclear cells. These optimal conditions and macrophage independence are different from those of mitogen-induced IFN production in canine lymphoid cells.