SPONTANEOUSLY GENERATED NON-HODGKINS-LYMPHOMA IN 27 SIMIAN T-CELL LEUKEMIA-VIRUS TYPE-1 ANTIBODY-POSITIVE BABOONS (PAPIO SPECIES)

Simian T-cell leukemia virus type 1 (STLV-1), a type C retrovirus asso ciated with leukemia/lymphoma in Old World monkeys, is closely related to human T-cell leukemia virus type 1, the etiologic agent of adult T -cell leukemia/lymphoma in humans. In a colony of 3200 baboons, the pr evalence of antibodies to STLV-1 is more than 40%. Seropositivity is m ore frequent in female baboons than in males and increases with age. O f 27 STLV-1 antibody-positive baboons with non-Hodgkin's lymphoma, 20 were females and 7 were males, ranging in age from 3 to 21 years (mean , 13 years). Non-Hodgkin's lymphoma was not found in STLV-1 antibody-n egative baboons. Clinical signs and laboratory findings were variable but generally included lethargy, low body weights, anemia, dyspnea, ly mphadenopathy, hepatosplenomegaly, pneumonia, nodular skin lesions, an d leukemia with or without multilobulated lymphocytes in peripheral bl ood. Radiography revealed pulmonary infiltrates consistent with pneumo nia in 17 of the baboons. Serum chemical values were normal except for hypercalcemia in one baboon. Lymphocytosis was found in 18 of the bab oons, with leukemia diagnosed in 11. At necropsy, variable enlargement of lymph nodes and other lymphopoietic tissue was usually found. Pale tan to white space-occupying foci typical of proliferative lymphoid t issue were often found in various organs, including lungs, spleens, li vers, skin, and hearts. The lungs in 14 baboons had thickened pleuras, congestion, edema, and large tan to brown areas of consolidation. His tologically, there was diffuse infiltration of lymph nodes, lungs, and other tissues by lymphoid cell populations classified by the Working Formulation of Non-Hodgkin's Lymphomas for Clinical Usage as large cel l, immunoblastic, polymorphous variant; large cell, immunoblastic; mix ed small and large cell; and small cell. Examination of tissues staine d with pan-B cell antigen L26, Beta-F1, and pan-T cell antigen UCHL1 i ndicated tissues for two non-Hodgkins lymphoma cases failed to stain f or T- or B-cell lymphoid antigens, 23 were of T-cell, and 2 of B-cell lineage. Cell surface immunofluorescence analysis of cells from periph eral blood and lymphoid organs confirmed T-cell lineage in the six non -Hodgkin's lymphoma cases evaluated. Baboons with non-Hodgkin's lympho ma had antibodies indicating infection with STLV-1. This information s uggests STLV-1 may be an etiologic agent of T-cell leukemia/lymphoma i n baboons and recommends the baboon as a model of adult T-cell leukemi a/lymphoma in humans.