Exploring the expression and diagnostic value of CD177 + neutrophils in tuberculosis patients

Background Granulocyte subsets, such as normal-density granulocytes(NDG) and low-density granulocytes(LDG), play an important role in the pathogenesis of tuberculosis (TB). CD177 ⁺ neutrophils were up-regulated during inflammation and tumour. However, the role of CD177 of neutrophils in TB patients remain elusive. This study aimed to explore the expression of CD177 ⁺  neutrophils in TB patients and assess the correlation between CD177 and clinical characteristics to determine the expression and diagnostic value of CD177 ⁺ neutrophils of tuberculosis patients. Methods The expression of CD177 of LDG and NDG were confirmed by flow cytometry in 42 TB patients and 26 healthy controls. The levels of markers related to granulocyte activation(CD66b) and immunosuppression programmed death receptor 1 (PD1) in CD177 ⁺ LDG and CD177 ⁺ NDG were compared in 27 TB patients. The levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, TNF-α, and IFN-γ were measured with cytokine profiling kits. Correlations with clinical characteristics, inflammatory markers and cytokines as well as receiver operating characteristic (ROC) curve analysis were determined. Results Flow cytometry analysis confirmed the elevated CD177 ⁺ LDG and low CD177 ⁺ NDG expression in TB patients compared with healthy controls. CD177 ⁺ LDG was characterized by high CD66b and low PD-1 expression and was significantly correlated with CD66b and culture filtrate protein 10 spot-forming cells (CFP-10 SFC), and CD177 ⁺ NDG is associated with PD1. In addition, the percentage of CD177 ⁺ LDG, the percentage of PD1 of CD177 ⁺ LDG, and MFI of PD1 of CD177 ⁺ LDG were all significantly increased in the EPTB group compared to the PTB group. The percentage of CD177 ⁺ NDG showed 90.00% sensitivity and 59.26% specificity with an AUC of 0.748 in distinguishing between patients with TB and HC, followed by the MFI of CD177 of LDG. Notably, MFI of PD1 on CD177 ⁺ LDG harbored the highest AUCs to differentiate EPTB and PTB with 70.00% sensitivity and 88.24% specificity(AUC = 0.818 ). These findings underscore the role of CD177 in granulocyte subsets of TB.