Immunologic abnormality in a group of Macaca arctoides with high mortality due to atypical mycobacterial and other disease processes.

Of 54 Macaca arctoides, 44 died during the 2.5 years after their assignment to a common cage. Although early deaths were due to trauma, acute gastric dilatation, and shigellosis; latter deaths were the result of a variety of uncommon diseases including atypical mycobacterial disease, malignant lymphoma, protozoan encephalomyelitis, and other necrotizing and inflammatory lesions. Atypical mycobacterial disease due to Mycobacterium avium intracellular serotypes was the most frequent single disease agent recognized (33% [18 macaques]). This disease began in the ileum and large intestine with subsequent systemic involvement. An abnormality of host response to infective agents, in general, was indicated by the unusually high occurrence of this disease, as well as other disease processes. Morphologic evaluation of lymphoid organs revealed decreased cellularity of follicles and decreased numbers of plasma cells in all macaques, whereas T cell-dependent areas varied from hypocellular to hypercellular with 5 macaques with malignant lymphoma. The spontaneous erythrocyte rosette-forming subpopulation of T cells was decreased in peripheral blood, but was increased in lymph nodes containing atypical mycobacterial lesions. Serum immunoglobulin value decreased progressively in diseased macaques. A basic abnormality of T-cell subpopulations controlling other components of host response was suspected. Macrophages from lesions that contain mycobacterial organisms did not phagocytize latex beads normally in vitro, whereas monocytes in the blood of the same macaques were capable of in vitro phagocytosis.