When the effect of obesity on significant changes in cytokines in experiments was examined across the four types of infectious challenges: for TNF, eight experiments reported significant increases and five decreases; for IL-1b, four reported increases and one a decrease in blood but an increase in lung tissue; for IL-6, five reported increases and one a decrease; for IL-10, two reported increases and one a decrease; and for MIP-2a, three reported increases and none a decrease. Here, IL6 is linked to obesity due to melanocortin 4 receptor deficiency.