Abstract: Objective To investigate the correlation between neutrophil/lymphocyte ratio (NLR) and the level of T cell immunity in patients with bronchopneumonia. 
Methods A total of 104 patients with bronchopneumonia were selected as the research group and 50 patients with bronchial foreign body were selected as the control group. According to the clinical examination results, the patients in the research group were divided into mild group (n=61) and severe group (n=43). The levels of NLR, cytokines ［interferon-γ (INF-γ)］, interleukin-4 (IL-4), INF-γ/IL-4 and T lymphocyte subsets (CD3+, CD4+, CD8+, CD4+/CD8+) were detected in all patients. The correlation between NLR and the level of T cell immunity in patients with bronchopneumonia was analyzed.  
Results NLR, INF-γ and INF-γ/IL-4 in mild and severe groups were higher than those in control group, and higher in severe group than in mild group (P＜0.05). CD3+, CD4+ and CD4+/CD8+ in mild and severe groups were lower than those in control group, and CD8+ was higher than that in control group; CD3+, CD4+ and CD4+/CD8+ in severe group were lower than those in mild group, and CD8+ was higher than that in mild group (P＜0.05). NLR was positively correlated with INF-γ and INF-γ/IL-4 in patients with bronchopneumonia (P＜0.05), and negatively correlated with CD4+ and CD4+/CD8+ (P＜0.05), which, however, had no correlation with IL-4, CD3+ and CD8+ (P＞0.05). 
Conclusion NLR is correlated with INF-γ, INF-γ/IL-4 and T lymphocyte subsets such as CD3+ and CD4+/CD8+. NLR can reflect the level of T cell immunity in patients with bronchopneumonia to a certain extent.

Key words: bronchopneumonia, neutrophil/lymphocyte ratio, T-lymphocytes