APOB and obesity due to melanocortin 4 receptor deficiency: Next, we performed ELISA measurements in order to characterize the anti-ApoB100/p210 autoimmune response throughout the evolution of obesity in mice fed a HFD; the autoantibody characterization outlined in the foregoing section allowed us to use pB4, which is more practical than ApoB100 or p210, as the diagnostic antigen.