While the combined genetic deletion of NKT and CD8+ T-cells improves glucose tolerance and reduces inflammation, interpretation of these data have been complicated by the recent observation that the deletion of CD8+ T-cells alone reduces obesity-induced inflammation and metabolic dysregulation, leaving the issue of the metabolic effects of NKT cell depletion unresolved. This evidence concerns the gene CD8A and obesity due to melanocortin 4 receptor deficiency.