EXPRESSION OF TNF-ALPHA IN ARTHRITIS CAUSED BY CAPRINE ARTHRITIS-ENCEPHALITIS VIRUS

Goats infected with caprine arthritis encephalitis virus (CAEV) develo p chronic arthritis sharing many features with human rheumatoid arthri tis (RA). TNF is thought to be a key mediator contributing to the form ation of the arthritic lesion in RA. We studied this cytokine in goats suffering from chronic arthritis. TNF alpha expressing cells were det ected by in situ hybridization in synovial membranes of arthritic carp al joints. Expression of TNF alpha did not correlate with the degree o f viral replication as assessed by in situ hybridization for viral RNA . In line with the lack of correlation between the degree of viral rep lication and TNF expression in vivo, we failed to detect increased cyt okine RNA in goat macrophages infected with CAE virus in vitro and no TNF protein was found in culture supernatants. In addition, virus infe ction failed to prime goat macrophages for enhanced TNF expression in response to lipopolysaccharide. Taken together, these findings argue a gainst a direct role of CAE virus in increasing the expression of TNF alpha in caprine arthritis.