Abstract DP116: Hematoma–Immune Interactions: Lymphocyte Percentage as an Independent Prognostic Marker Enhanced by Imaging in ICH

Background: Spontaneous intracerebral hemorrhage (ICH) is the most devastating stroke subtype. Early prediction of functional outcomes is critical for personalized treatment. Immune-inflammatory responses, particularly T cell–mediated adaptive immunity, contribute to secondary brain injury via hematoma-related inflammation, BBB disruption, and perihematomal edema (PHE). While most studies focus on total leukocyte or neutrophil counts, the prognostic significance of specific T-cell subsets remains unclear, especially when integrated with quantitative imaging metrics. This study evaluated the prognostic value of peripheral % lymphocyte versus individual T-cell subsets (CD3 + , CD4 + , CD8 + ) and their interaction with hematoma/edema burden in predicting short-term functional outcomes after ICH. Methods: We retrospectively analyzed 228 ICH patients (165 males; ≤45 years: n=153). Admission blood samples measured CD3, CD4, CD8 counts, CD4/CD8 ratio, and lymphocyte %. CT quantified hematoma and edema volumes; PHE index and grades were calculated. Discharge NIHSS and mRS scores were recorded. Associations between immune markers, imaging parameters, and outcomes were assessed using multivariate regression, subgroup, and mediation analyses. Results: Lymphocyte% correlated inversely with edema volume (r=−0.25) and both mRS and NIHSS at discharge (r=−0.40, all P