To investigate the role of NKT cells in the development of obesity-related metabolic disturbances in the absence of alterations in CD8+ T-cells, we utilized the CD1d knockout mouse line, which lacks NKT cells, but has a full complement of CD8+ T-cells, as opposed to the β2-microglobulin knockout mouse used in a previous study, which lack both NKT and CD8+ T-cells[13]. The gene discussed is CD1D; the disease is obesity due to melanocortin 4 receptor deficiency.