CX3CL1 and respiratory syncytial virus bronchiolitis: No significant differences were observed in the plasma levels of CCL1, CCL7, CCL8, CCL18, CCL19, CCL22, and CX3CL1 between the RSV bronchiolitis group and the control group, or between the non-recurrent wheezing and recurrent wheezing groups (P > 0.05) (Fig. 4).