Expression of Fcγ receptors by rheumatoid and age/sex-matched control leucocytes. Baseline expression of FcγRIIIb (a) or FcγRIIa (b) in patients with rheumatoid arthritis (RA) and in controls. Blood was analysed for the baseline expression of FcγRIII on circulating leucocytes in an RA population and compared with a control. FcγRIIa was found to be higher on resting monocytes from patients with RA (p < 0.05; RA, n = 18; control, n = 18). Each experiment was performed in duplicate. (c) Change in FcγRIIIb expression on neutrophils in response to TNF-α. Two-way analysis of variance revealed no difference in the modulation of FcγRIIIb between RA and controls after stimulation with TNF-α. Results are expressed as the percentage change from the baseline expression (mean ± SE). Each experiment was performed in duplicate. MESF, milliequivalents of soluble fluorescein.