ROLE OF T-LYMPHOCYTES IN EXPERIMENTAL STAPHYLOCOCCUS-AUREUS ARTHRITIS

Using a recently developed murine model of haematogenously induced Sta phylococcus aureus, the authors have characterized the phenotypes and functional properties of inflammatory cells present in the synovium of arthritic mice. The results show that large numbers of granulocytes a nd macrophages were observed in the inflamed synovia within 24 h of in oculation of S. aureus strain LS-1. Many of the synovial macrophage-li ke cells stained for cytoplasmic IL-1 alpha and TNF-alpha. Subsequentl y (greater than or equal to 48 h later), a prominent infiltration of T lymphocytes, predominantly of CD4(+) phenotype, was observed. Some of the T lymphocytes stained for IL-2 receptor and intracytoplasmic inte rferon-gamma (IFN-gamma). Surprisingly, in spite of the severe inflamm atory process, very few cells expressed MHC class-II molecules in the arthritic synovia. In addition, in vivo depletion of CD4(+) T-cells re sulted in a considerably milder course of staphylococcal arthritis. Th e similarities in the phenotype expression of synovial cells and centr al role of T-cells in S. aureus arthritis as well as in non-infectious models of arthritis, indicate that the process governing joint destru ction is likely to be the same, irrespective of the initial stimulus.