CD28 and metabolic syndrome: Patients with metabolic comorbidities, including hypertension (30.11% vs. 39.71%, p = 0.020), dyslipidemia (30.59% vs. 42.75%, p = 0.002), or atherosclerosis (29.54% vs. 39.02%, p = 0.030), exhibited significantly lower proportions of CD28+PD1−/CD8+ T cells in PBMC compared to those without these conditions (Figure 2K).