Effect of nutritional copper deficiency on adjuvant arthritis and immunocompetence in the rat

Both severe and marginal copper deficiency were produced in male Sprague Dawley rats prior to induction of adjuvant arthritis. Degree of copper deficiency was confirmed by analysis of plasma, liver, and brain samples prior to adjuvant injection. Incidence of adjuvant arthritis was the same in both copper deficient and control animals although the severity was slightly but not statistically less in the former. However, recovery from foot edema was impaired in copper-deficient animals, while marginally copper-deficient animals recovered at the same rate as did controls. Plasma copper concentration increased in response to the injection of adjuvant and the increase was directly related to dietary copper content. Plasma zinc concentration was decreased in arthritic animals and the decrease was inversely correlated to paw edema. Liver copper, zinc, and iron concentrations in arthritic animals remained unchanged or increased slightly in comparison to the corresponding non-injected controls. Copper-deficient rats were immunosuppressed as demonstrated by impaired responsiveness to the T-cell dependent contact sensitizing agent oxazolone and diminished capacity to respond to the T-cell independent antigen Type III pneumococcal polysaccharide. Although a statistical difference in paw volumes was not found for group of animals fed diets differing in copper content, it is postulated that copper deficiency may alter the severity and kinetics of adjuvant arthritis by impairing aspects of the immune response and the tissue repair processes subsequent to injury.