Vitamin A deficiency: serum cortisol and humoral immunity in lambs.
Serum cortisol and antigen-specific and polyclonal immunoglobulin G (IgG) concentrations were measured to investigate the relationship between vitamin A status and immune function in lambs. Twenty-four 3-mo-old crossbred ewe lambs weighing approximately 10 kg were each fed 900 g/d of a carotene-deficient diet. The 12 control lambs also received a 100,000 IU oral dose of vitamin A palmitate every 2 wk. All lambs were given primary and secondary antigenic challenges. Lambs were slaughtered at the end of the secondary challenge period. Liver vitamin A concentrations were greater (P less than .001) in the control animals (69.5 vs 1.3 micrograms/g wet tissue). Both groups of lambs exhibited a similar growth response until d 105, after which daily gain of the control lambs exceeded (P less than .03) that of the A-deficient lambs. Polyclonal serum IgG concentrations were greater (P less than .05) in the A-deficient lambs on d 49 to 124 and on d 151 (P less than .10). Ovalbumin-specific serum IgG concentrations tended to be greater in the control lambs throughout the primary and secondary challenge periods. Control lambs had greater titers on d 164 (P less than .07) and d 190 (P less than .03). Vitamin A status appeared to have no consistent effects on serum cortisol concentrations. Spleen weights were greater (P less than .002) in the A-deficient lambs. Lungs from 11 of 12 A-deficient lambs contained abscesses, as opposed to 1 of 12 for the control lambs. Both polyclonal and antigen-specific IgG concentrations were affected by vitamin A status. Serum cortisol concentrations did not appear to mediate this effect.
Bruns
N J
NJ
Virginia Polytechnic Institute and State University, Blacksburg 24061.
Webb
K E
KE
D000818:Animals; D000918:Antibody Specificity; D001835:Body Weight; D005260:Female; D006854:Hydrocortisone / Q000097:blood*; D007074:Immunoglobulin G / Q000032:analysis*; D010047:Ovalbumin / Q000276:immunology; D011897:Random Allocation; D012756:Sheep; D012757:Sheep Diseases / Q000097:blood / Q000276:immunology*; D014801:Vitamin A / Q000097:blood; D014802:Vitamin A Deficiency / Q000097:blood / Q000276:immunology / Q000662:veterinary*
D007074:Immunoglobulin G; D014801:Vitamin A; D010047:Ovalbumin; D006854:Hydrocortisone