Increased T cell activation in BALF from children with Mycoplasma pneumoniae pneumonia

Summary Background and objective The mechanisms of Mycoplasma pneumoniae induced lung inflammation are not clearly understood yet. This study investigated whether activated T cells in the airway contributed to the pulmonary inflammation in patients with severe Mycoplasma pneumoniae pneumonia (MPP). Methods BALF were collected in all 45 patients with MPP (MPP, n = 45), including mild (Mild, n = 20) and severe (Severe, n = 25) group. BALF in 20 of all 25 severe cases with MPP at the recovery stage (Rec‐severe, n = 20) were collected again. The control group consisted of 20 patients with airway foreign body aspiration (Con., n = 20). CD3+ T cells, CD69+, HLA‐DR+, CD25+ on CD3+ T cells in BALF were determined by flow cytometry. Levels of IL‐6, IL‐10 in BALF were determined by ELISA, and percentage of neutrophils was counted. Results A significant increased percentage of neutrophils and levels of IL‐6 and IL‐10, decreased percentage of CD3+ T cells, increased expressions of CD69+, HLA‐DR+ or CD25+ on CD3+ T cells were observed in children with MPP compared with the control group (P