FPR2 and chronic obstructive pulmonary disease: FPR2 expression on helper T cell (19.8 ± 6.6 vs. 9.2 ± 2.3 MFI, p = 0.004, Fig. 3i) and FPR3 expression of M1 monocyte (9.5 ± 1.9 vs. 5.2 ± 1.7 MFI, p = 0.007, Fig. 3j) after 1-year treatment were both higher in COPD patients on oral steroid for more than 3 months than that in those without oral steroid use.