Characterizing immune cell subsets in lung adenocarcinoma

This study aimed to comprehensively profile immune cell populations across peripheral blood, tumor tissue, and non-tumoral adjacent lung tissue from patients with lung adenocarcinoma (LUAD) and to identify patterns of tumor-infiltrating immune cells that distinguish patient subgroups. Peripheral blood, tumor, and adjacent lung tissue were collected from 48 treatment-naïve or recently treated LUAD patients (stages I–IV, equally male and female) and analyzed by CyTOF using 44 immune surface markers to resolve major lymphoid and myeloid populations. Initial clustering defined 20 broad immune lineages, which were re-clustered into 66 distinct CD45+ cell subsets, and paired comparisons between tissues identified subsets enriched or depleted in tumors. Sixteen subsets—predominantly differentiated B cell populations—were consistently elevated in tumors relative to both blood and adjacent tissue, while several senescent CD8+, NK, and myeloid populations were depleted. Principal component analysis revealed distinct immune profiles for each tissue, with the greatest variability in tumor samples driven by tumor-infiltrating subsets. Unsupervised k-means clustering of tumor immune profiles identified four patient groups: Group 1 tumors were enriched in multiple activated and antigen-presenting B cell subsets with higher CD4+ central memory T cells; Group 2 was enriched in CD8+ resident memory T cells; Group 3 was dominated by CD4+ activated effector (Th1-like) cells; and Group 4 showed high myeloid and NK cell populations with naïve and TEMRA T cells, suggestive of an immunologically inactive tumor microenvironment. Further analysis of 15 B cell clusters revealed subgroup-specific distributions beyond overall B cell abundance, indicating that both the quantity and composition of B cell subsets contribute to distinct tumor immune landscapes across LUAD patients.