Objective:This study aims to analyze the counts (per kilogram of body weight) or percentages of transplanted lymphocyte subgroups in children with non-infectious pulmonary complications (NIPC) and air-leak syndrome (ALS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and explore its significance in the progression of lung complications after transplantation.Methods:The patients with NIPC and ALS after allo-HSCT from January 2013 to December 2019 in Hebei Yanda Ludaopei Hospital were retrospectively studied and the influencing factors in the progress of NIPC after HSCT were statistically analyzed.Results:Of the 2026 children who received HSCT treatment, 59 patients (34 males and 25 females) developed NIPC, the probability was 2.9% (59/2 026), and the probability of combined ALS was 1.4% (28/206). The differences in the comparison between NIPC progressed to ALS group (ALS group) and failed to progress to ALS group (non-ALS group) in the patient′s age( P=0.028), disease condition before transplantation( P=0.022), NIPC onset time( P=0.004) were significant. The P values of the percentage of NKT-like cells in the bone marrow ( P=0.008) or peripheral stem cells ( P=0.003) accounted for the lymphocytes. CD4+CD25+dim cells in bone marrow ( P=0.029) or peripheral stem cells ( P=0.036) accounted for the CD4+lymphocytes and the ratio of CD4/CD8 in bone marrow( P=0.004) or peripheral stem cells ( P=0.020) were less than 0.05, which meant the differences in patients′ refusion cells were significant. In the binary logistic regression model, the percentage of bone marrow NKT-like cells to lymphocytes, the ratio of bone marrow CD4+/CD8+and the percentage of peripheral stem NK cells to lymphocytes were important risk factors for the progression of NIPC to ALS. The rest factors were excluded from the model (AUC=0.918, P<0.05). Conclusion:During allo-HSCT transplantation, a high proportion of NKT-like cell and NK cell levels, and a high CD4+/CD8+ratio in the infusion of donors with high immune tolerance have an important correlation with the progression of the NIPC.