Novel in vitro effects of bucillamine: Inhibitory effects on proinflammatory cytokine production and transendothelial migration of T cells

Objective To investigate the novel antiinflammatory mechanism of a disease‐modifying antirheumatic drug, bucillamine, on activated T cells, specifically its effect on T cell proliferation, cytokine production, and migration of T cells. Methods T cells were cultured in wells coated with anti‐CD3 monoclonal antibodies (mAb) plus anti‐CD26 mAb or anti‐CD3 plus anti‐CD28 mAb, with or without bucillamine. Proliferative responses and the production of interleukin‐2 (IL‐2), interferon‐γ (IFNγ), tumor necrosis factor α (TNFα), IL‐6, IL‐4, and IL‐5 were measured under these costimulatory conditions. Phytohemagglutinin (PHA)–activated T cells were cultured on human umbilical vein endothelial cell–coated transwells in the presence or absence of bucillamine, and T cells migrating through the endothelial cell layer were counted. Immunofluorescence analysis was also performed to analyze the effect of bucillamine on the surface expression of adhesion molecules on T cells. Results Bucillamine (64 μM) significantly inhibited T cell proliferation and the production of IL‐2, IFNγ, TNFα, and IL‐6, whereas it had no inhibitory effects on the production of IL‐4 and IL‐5 in the cultures with anti‐CD3 plus anti‐CD26 mAb. In contrast, bucillamine had no effects on T cell proliferation or any cytokine production in the cultures with anti‐CD3 plus anti‐CD28 mAb. Furthermore, the same concentration of bucillamine inhibited transendothelial migration of PHA‐activated T cells, and reduced the expression level of CD44 on T cells. Conclusion This study demonstrated the novel effects of bucillamine in vitro, showing inhibition of type 1 T helper–type cytokine production and proinflammatory cytokine production induced by certain costimulatory conditions, and inhibition of transendothelial migration of T cells. The inhibition of T cell migration appeared to be mediated partly through the reduced expression of CD44, an adhesion molecule on the T cell surface.