Increased Macrophage Division in the Synovial Fluid of Goats Infected with Caprine Arthritis-Encephalitis Virus

Publisher Website
Google Scholar
Abstract
Macrophages are a major component of the arthritic lesions induced by the lentivirus caprine arthritis-encephalitis virus (CAEV). Using autoradiography and the appearance of mitotic figures to detect dividing macrophages, we found that 2.1% ± 0.2% of synovial fluid macrophages from uninfected goats are dividing and that after infection with CAEV the percentage increases three- to sixfold. The enhanced macrophage division was not associated with increased dividing of blood monoblasts. The amount of macrophage division correlated with two measures of arthritis: joint swelling and the number of synovial fluid macrophages. Induction of an immune response in the joints of CAEV-infected goats increased the number of dividing macrophages. The synovial fluid of infected animals was mitogenic for macrophages from infected animals in amounts that correlated with the amount of macrophage division occurring in the joints. Activated lymphocytes produced nondialyzable lymphokines mitogenic for macrophages from CAEV-infected goats but not from uninfected goats. These results suggest that in situ macrophage division contributes to the lesions induced by CAEV and that infection leads to greater responsiveness of macrophages to mitogenic factors produced by lymphocytes.