Single-cell dissection of pleural and systemic immunity uncovers pathogen-specific immune reprogramming in tuberculosis versus lung adenocarcinoma.

To dissect how malignant versus infectious pleural disease reshapes local and systemic immunity, we compared lung adenocarcinoma with tuberculosis using matched pleural effusions and peripheral blood from patients and healthy controls using single cell transcriptome analysis and TCR clonotype tracking. Th1/17 polarized pro-inflammation dominating TB effusions, while their precursors, the recently activated CD4 T cells, adopt an antitumor trajectory in LUAD, but their recruitment and clonal expansion were effectively suppressed. In both diseases, CD8⁺ T cells diverged into GZMH⁺ and GZMK⁺ subsets. The former served as the antitumor killer cells but suppressed by multiple anti-inflammatory signals especially from the extracellular matrix in LUAD. The later could serve as stem-like precursors. MAITs and class-switched B cells both exhibited higher levels of activation and expanded in TB. Myeloid cells were mostly recovered from peripheral bloods and showed heightened activation in TB, upregulating TNFRSF14, TNFRSF13B, and pro-inflammatory cytokines (CXCL2, CXCL3, IL1), while LUAD featured immunosuppressive signals including MDK-NCL, FN1-CD44, and THBS1-CD47. Cell-cell communication highlighted LUAD-enriched outgoing interaction strengths by myeloid cells including monocytes and DCs, through IL16 and VISFATIN signaling, which strongly corelated with survivals. In conclusion, both pleural effusions and peripheral blood from TB and LUAD exhibit significant distinct immune landscapes. These results delineate disease-specific molecular mechanisms underlying immune regulation in pleural malignancies and infections.