Infliximab regulates monocytes and regulatory T cells in Kawasaki disease

Background The effect of infliximab ( IFX ) on immune cells has not been fully reported in Kawasaki disease ( KD ). To investigate the mechanism of IFX in KD , we examined changes in the abundance of CD 14 + CD 16 + activated monocytes, regulatory T cells (T reg ) cells, and T‐helper type 17 (Th17) cells following treatment with IFX . Methods We collected peripheral blood from patients with i.v. immunoglobulin ( IVIG )‐resistant KD and analyzed absolute CD 14 + CD 16 + monocyte, T reg ( CD 4 + CD 25 + FOXP 3 + ) and Th17 cell ( CD 4 + IL ‐17A + ) counts on flow cytometry. We also measured changes in serum soluble interleukin ( IL )‐2 receptor ( IL ‐2R), IL ‐6, and tumor necrosis factor ( TNF )‐α on enzyme‐linked immunosorbent assay. Results T reg cells and Th17 cells significantly increased after IFX treatment compared with baseline (126 ± 85 cells/μL vs 62 ± 53 cells/μL, P < 0.01; 100 ± 111 cells/μL vs 28 ± 27 cells/μL, P < 0.05, respectively). In contrast, in a subgroup of patients with CD 14 + CD 16 + monocytes above the normal range before IFX , the CD 14 + CD 16 + monocytes significantly decreased following IFX treatment (72 ± 51 cells/μL vs 242 ± 156 cells/μL, P < 0.05).. Serum TNF ‐α did not change, but soluble IL ‐2R and IL ‐6 decreased after IFX treatment. Conclusion IFX could downregulate activated monocytes and upregulate T reg cells towards the normal range. IFX treatment thus contributes to the process of attenuating inflammation in KD .