A more recent study investigated the effect of T cell co-stimulation blockade on obesity-associated insulin resistance, and found that both CD40L antibody and cytotoxic T lymphocyte antigen 4 (CTLA-4) immunoglobulin (Ig)-treated diet-induced obese mice had reduced numbers of VAT macrophages and CD8+ T cells, as compared to obese mice treated with control antibody (73). This evidence concerns the gene CD8A and obesity due to melanocortin 4 receptor deficiency.