Abstract: Objective To investigate the changes of lymphocyte immune function of pulmonary alveolar lavage fluid (BALF) in patients with pulmonary tuberculosis by flow cytometry. Method 19 pediatric tuberculosis patients were enrolled, according to sputum smear results, they were divided into bacteria positive group (11 cases) and bacteria negative group (8 cases). 21 adult tuberculosis patients were selected as the control group. Flow cytometry was used to detect the changes in the proportion of lymphocytes, CD4⁺T cells, CD8⁺T cells, monocytes and B lymphocytes in Balf of the two groups, and the differences were compared. Result The proportion of immune cells in Balf of children with tuberculosis was as follow: The proportion of T lymphocytes was (54.57±5.28)%, CD4⁺T cells (66.14±4.08)%, CD8⁺T cells (33.80±4.07)% and B cells (13.54±2.53)% pediatric tuberculosis patients. The proportion of T lymphocytes was (53.30±4.76)%, CD4⁺T cells (65.45±3.49)%, CD8⁺T cells (34.55±3.49)% and B cells (14.70±2.83)% in adult pulmonary tuberculosis patients. There was no statistical significance between the two groups (P>0.05). There was no difference in the ratio of CD4⁺/CD8⁺T cells between two groups (P>0.05). The monocytes of children tuberculosis patients (16.00±3.20)% were significantly higher than those of adult tuberculosis patients (9.25±1.17), and the difference was statistically significant (P<0.05). The proportion of CD4⁺T lymphocyte was (65.64±5.41)%, CD8⁺T lymphocyte （34.36±5.41）% and monocyte (19.15±5.18)% in the Balf of the positive of bacteriology subgroup of pediatric tuberculosis patients. The proportion of CD4⁺T lymphocyte was (66.84±6.65)% , CD8⁺T lymphocyte (33.03±6.58)% and monocyte (11.75±1.75)% in the negative of bacteriology subgroup of pediatric tuberculosis patients. There was no statistical significance (P>0.05). However, The proportion of T lymphocyte was (45.06±6.38)% and B cells (9.30±2.60)% in positive of bacteriology subgroup were significantly lower than those in the negative group [(67.64±6.93)% and (21.48±4.17)%], respectively, and the difference was statistically significant (P<0.05). Conclusion Monocytes from pediatric patients with pulmonary tuberculosis were higher than those in adult pulmonary tuberculosis patients;The proportion of B lymphocytes in pediatric TB patients with sputum smear bacteria positive was significantly lower than in sputum smear bacteria negative patients. It suggests that the immune function of active children with tuberculosis has decreased, which provides some theoretical basis for understanding the pathogenesis of pulmonary tuberculosis and for clinical immunotherapy.

Key words: Tuberculosis, Children with tuberculosis, Bronchoalveolar lavage fluid, Cellular immunity, Immune cells