Monitoring of interleukin-2 receptor (IL-2R) expression in vivo and studies on an IL-2R-directed immunosuppressive therapy of active and adoptive adjuvant-induced arthritis in rats.

Recent evidence indicates that adjuvant arthritis (AA) of rats induced by complete Freund's adjuvant (CFA) is an autoimmune disease that is mediated by T cells. This report describes the distribution of activated IL-2 receptor (IL-2R)-bearing cells in spleen, popliteal lymph nodes (PLN) and blood in AA rats and in naive healthy rats using the monoclonal antibody (mAb) ART-18. It was found that in the primary lymph nodes (injected side) two peaks of elevated numbers of IL-2R-positive cells (Day 9/10 with a 40-fold increase; Day 25 with a 75-80-fold increase) occur. The PLN of the non-injected site also show an increase (30-fold) in the number of IL-2R-positive cells on Day 25. This investigation also included the monitoring of soluble IL-2R in the serum of AA rats in comparison to control sera of non-induced rats. The incidence of free IL-2R in the serum of AA rats does not completely correlate with the pattern of the distribution of receptor-bearing cells in PLN; elevated levels of IL-2R were observed at Day 9 and subsequently declined to below control levels. On Day 25, there was no correlation between IL-2R+ cells and soluble IL-2R. ART-18 was not active in suppressing the development of AA, in contrast to the complete inhibition of the passively transferred AA.