Peripheral lymphocyte subset profiles associated with Traditional Chinese Medicine constitution in 853 adults: a cross-sectional study.

BACKGROUND: The Traditional Chinese Medicine (TCM) constitution framework classifies adults as Pinghe (balanced constitution) or as having one or more biased constitution patterns. Whether these questionnaire-based categories correspond to peripheral immune-cell composition remains unclear. METHODS: We analysed 853 adults in a cross-sectional study with TCM constitution classification and flow-cytometry lymphocyte subset percentages. Constitution variables were analysed as binary indicators. Group differences were summarized with effect sizes, 95% confidence intervals (CI), Mann-Whitney U tests, false discovery rate correction, and age- and sex-adjusted regression. A self-developed KNN-graph Deep Graph Infomax model was used as a secondary internal classification analysis. RESULTS: Pinghe was present in 569 participants (66.7%, 95% CI 63.5-69.8), and 284 participants were non-Pinghe. No individual immune-cell marker remained significant after false discovery rate correction. Pinghe participants showed a higher total CD3-CD56+ natural killer-cell percentage and a lower total CD3+ T-cell percentage than non-Pinghe participants, with small effect sizes. The post hoc total NK-cell/total T-cell ratio was higher in Pinghe after adjustment for age and sex. The deep-learning model showed moderate internal discrimination but requires external validation. CONCLUSION: Pinghe constitution was associated with limited differences in peripheral lymphocyte composition. Longitudinal and functional immune studies are needed to determine whether these small differences reflect stable constitution-related immune profiles.