CD4 and obesity due to melanocortin 4 receptor deficiency: Importantly, the presence of comorbidities and/or obesity did not significantly alter the linear correlation between age and CD38 and CCR6 expression by CD4+ T cells or CXCR5 and CD69 expression by B cells, indicating that the differences that we identified in our study are indeed driven by age and not a function of confounding comorbidities.