Fig. 1

Downregulation of CD64/FcγRI on monocytes after exposure to abatacept, as shown by flow cytometry. Peripheral blood monocytes were cultured for 24 h in the absence (mock) or presence of abatacept (ABT) or CD28-Ig and the expression of CD64/FcγRI (A) and CD80, CD86, and CXCR2 (B) was examined by flow cytometry. Peripheral blood monocytes were obtained from 20 patients with RA and 8 controls and used for a validation experiment. The cell surface expression is expressed as the mean fluorescence intensity (MFI) ratio. A representative histogram showing the expression of CD64/FcγRI in a patient with RA and a control is also shown. The results are shown in boxplots, and statistical comparisons between the two groups were made using the Mann–Whitney U test