New disease-modifying antirheumatic drug 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298) selectively augments activation-induced T cell death

We examined in this study whether the newly developed disease-modifying ant irheumatic drug (DMBRD) 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298) augments activation-induced T cell death. Peripheral blood ( PB)T cells, isolated from healthy donors, were activated by incubation with interleukin-2 (IL-2) followed by further culture with 12-0-tetradecanoyl p horbol 13-acetate (PMA) and ionomycin in the presence or absence of KE-298. The apoptosis of activated T cells was examined by flow cytometric determi nation of hypodiploid DNA. Fas expression and caspase-3 activity in activat ed T cells were also examined by flow cytometry, and expression of Pas liga nd (FasL), Bcl-2-related proteins, and X chromosome-linked inhibitor of apo ptosis protein (XIAP) was determined by Western blot analysis. Apoptosis wa s not obvious in resting T cells and was not augmented by KE-298. In contra st, apoptosis was clearly detected in activated T cells (activation-induced T cell death) with the increment of caspase-3 activity, and incubation of these cells with KE-298 further enhanced apoptosis. Treatment of activated T cells with KE-298 increased Bar expression but decreased XIAP expression without affecting the expression of Fas/FasL. Thus caspase-3 activity in ac tivated T cells appeared to be increased by KE-298. Our results :suggest th at the newly developed DMARD, KE-298, selectively augmented activation-indu ced T cell death. This finding may contribute to the therapeutic efficacy o f KE-298 in rheumatoid arthritis (RA) patients and provide new insight into the pharmacologic action of DMARDs.