Another example of calorie restriction improving immune system performance, this time in humans rather than other primates: "Calorie restriction (CR) enhances immune response and prolongs life span in animals. However, information on the applicability of these results to humans is limited. T-cell function declines with age. We examined effects of CR on T-cell function in humans. Forty-six overweight, nonobese participants aged 20–42 years were randomly assigned to 30% or 10% CR group for 6 months. Delayed-type hypersensitivity (DTH), T-cell proliferation (TP), and prostaglandin E2 (PGE2) productions were determined before and after CR. DTH and TP to T-cell mitogens were increased in both groups over baseline. However, number of positive responses to DTH antigens and TP to anti-CD3 reached statistical significance only after 30% CR. Lipopolysaccharide-stimulated PGE2 was reduced in both groups but reached statistical significance after 30% CR. These results, for the first time, show that 6-month CR in humans improves T-cell function." Mild CR provides only mild benefits, as we would expect.

Link: http://dx.doi.org/10.1093/gerona/glp101