Two cases of ulcerative colitis that developed while using abatacept.

Abatacept (ABT) is a recombinant fusion protein consisting of the Fc domain fragment of human IgG1 and the extracellular domain of human cytotoxic T lymphocyte antigen-4 (CTLA-4). The function of ABT is similar to that of CTLA-4, which selectively regulates T-cell activation by inhibiting the co-stimulation of CD80/CD86 on antigen-presenting cells and CD28 on T lymphocytes. ABT is used for the treatment of rheumatoid arthritis (RA) and juvenile idiopathic arthritis.

Selective recruitment of CXCR3+ and CCR5+ CCR4+ T cells into synovial tissue in patients with rheumatoid arthritis.

The inflamed synovial tissue (ST) of rheumatoid arthritis (RA) is characterized by the selective accumulation of interferon gamma-producing Th1-type CD4+ T cells. In this study, we investigated whether the predominance of Th1-type CD4+ cells in the ST lesion is mediated by their selective recruitment through Th1 cell-associated chemokine receptors CXCR3 and CCR5. The lymphocyte aggregates in the ST of RA contained a large number of CD4+ T cells, which mostly expressed both CXCR3 and CCR5, but not CCR4.