CD4 and obesity due to melanocortin 4 receptor deficiency: Based on our observation that inhibition of T cell responses with topical tacrolimus markedly decreases adipose tissue inflammatory cell accumulation and improves lymphatic function, as well as previous studies demonstrating that CD4+ cells have profound anti-lymphangiogenic effects, we next sought to determine how loss of CD4+ cells modulates the effects of HFD on obesity and lymphatic dysfunction.