Comparative analysis of lymphocyte subsets in tuberculosis, NTM infections, and other respiratory diseases

Objective This study aimed to analyze the differences in lymphocyte subsets and immune function between tuberculosis (TB) and nontuberculous mycobacterial pulmonary disease (NTM-PD), thereby deepening the understanding of the pathogenesis of these diseases and providing important insights for clinical diagnosis, treatment, and prognosis evaluation. Methods Patients with pulmonary imaging abnormalities admitted to the Tuberculosis Department of Shanghai Pulmonary Hospital from January 2023 to December 2023 were included. Based on diagnostic assessments, they were categorized into active tuberculosis (ATB), NTM-PD, and other pulmonary diseases (including inflammatory and neoplastic lung diseases). Flow cytometry was used to detect lymphocyte subset counts. Results (1) There were no significant differences in lymphocyte subset counts between the ATB and NTM groups; however, both groups showed marked differences when compared with the group of patients with other respiratory diseases. Specifically, the percentages and absolute counts of CD3 + T cells, CD4 + T cells, CD8 + T cells, and CD19 + B cells were significantly lower in the ATB and NTM groups, whereas the levels of CD16 + 56 + natural killer (NK) cells were higher compared to those with other respiratory diseases.(2) Patients in the non-severe ATB (nSATB) group exhibited higher levels of CD3 + T cells and CD19 + B cells compared to those in the severe ATB (SATB) group.(3) Among patients with ATB, those with concomitant diabetes had lower CD8 + T cell counts and percentages, as well as a higher CD4/CD8 ratio, compared to those without diabetes.(4) In patients with NTM-PD, those with severe disease had lower percentages of CD16 + 56 + NK cells than those with non-severe NTM-PD.(5) No significant differences in lymphocyte subset parameters were observed between drug-resistant and drug-sensitive ATB patients, or between patients with rapidly growing and slowly growing NTM species. Conclusion This study revealed the lymphocyte subset characteristics of patients with TB and NTM infections and identified potential associations between disease severity, diabetes comorbidities, and immune cell subsets with disease status. These findings provide a basis for further research on the immune mechanisms of infectious pulmonary diseases and contribute to the development of precision medicine strategies.