Feline malignant lymphomas: comparison of morphologic and immunologic characteristics.

Lymphoid cell populations from various hematopoietic tissues of normal cats (n = 22) and from cats with malignant lymphoma (n = 14 cats) were examined simultaneously for morphologic and immunologic features. Scanning electron microscopy and mitogen stimulation studies were not useful in identifying the B or T cell nature of malignant lymphomas. Cell markers successfully used to identify B cells were the presence of surface immunoglobulin by fluorescent-immunoglobulin staining procedures and the presence of complement receptors by EAC (erythrocyte, antibody, complement) rosette formation. The formation of rosettes with guinea pig erythrocytes was used to identify T cells. Using these cell surface markers, thymic lymphomas were found to be composed of T cells and alimentary lymphomas were found to be composed of B cells. The multicentric lymphomas lacked B or T cell surface markers. Classification by cytologic type of cell did not show any correlation with other values.