# Comparative immunophenotyping of peripheral blood lymphocyte subsets in pulmonary tuberculosis and nontuberculous mycobacterial pulmonary disease: a retrospective study

## TL;DR

This study compares immune cell profiles in blood from patients with tuberculosis and non-tuberculous mycobacterial lung disease to identify potential diagnostic markers.

## Contribution

The study identifies distinct lymphocyte subset differences between PTB and NTMPD patients, suggesting immune profiling could aid diagnosis.

## Key findings

- PTB patients had higher CD4+ lymphocyte counts compared to NTMPD patients.
- CD4+ lymphocytes showed moderate diagnostic accuracy with an AUC of 0.722.
- Immune profiling differences suggest potential for improving diagnostic algorithms.

## Abstract

To compare peripheral blood lymphocyte profiles between pulmonary tuberculosis (PTB) and nontuberculous mycobacterial pulmonary disease (NTMPD) patients and explore whether these immunophenotypic differences may assist future diagnostic algorithms.

This retrospective study analyzed clinical data of 78 PTB patients, 73 NTMPD patients, and 80 healthy controls from the Shanghai Public Health Clinical Center between February 2024 and February 2025. Peripheral blood lymphocyte subsets were measured using flow cytometry. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to identify and assess diagnostic markers.

No significant differences in age or body mass index (BMI) were found among the three groups (P > 0.05), but gender distribution differed significantly (P < 0.05). PTB patients had a higher proportion of diabetes mellitus (P < 0.05), while NTMPD patients had a higher prevalence of structural lung disease (P < 0.05). PTB patients also showed higher platelet counts and CD3+, CD4+, and CD45+ lymphocyte counts (gated within the CD45+SSC-Alow population) compared to NTMPD patients (all P < 0.05). ROC analysis indicated that CD4+ lymphocytes had an area under the curve (AUC) of 0.722, with a sensitivity of 65.9% and specificity of 76.7%.

Significant differences in peripheral blood lymphocyte subsets exist between PTB and NTMPD patients. The CD4+ counts differed significantly between the two diseases, suggesting that immune profiling could contribute to a broader diagnostic framework once prospectively validated.