Routine Blood Biomarkers and CD4⁺ T-Cell States in Atherosclerosis: A Narrative Review and Conceptual Framework.

Background: Atherosclerosis (AS) is a chronic inflammatory disease driven by complex immune responses. Among the involved immune cells, CD4⁺ T cells are closely associated with plaque progression. An imbalance between inflammatory and regulatory T-cell responses can sustain vascular inflammation. However, the relationship between routinely measured blood biomarkers and these T-cell states remains unclear. Main Body: This narrative review examines how LDL-C, HDL-C, HbA1c, high-sensitivity C-reactive protein (hsCRP) and creatinine relate to biological processes involved in CD4⁺ T-cell regulation. We propose the T-cell Perturbation Index (TPI) as an unvalidated conceptual framework for generating hypotheses about these relationships. The candidate variables are informed by heterogeneous human and experimental studies. These studies do not provide comparable estimates from which numerical weights can be derived. The symbolic expression therefore assigns no numerical coefficients or individual immune-state classifications. Conclusion: The TPI organizes questions about the joint association of routine blood markers with CD4⁺ T-cell states in atherosclerosis. Whether these measurements capture reproducible immune variation remains unknown. Evaluation against direct immune measurements is required, and any clinical or prognostic application would require separate evidence.