Nutrition disorders and immunologic parameters: Study of the thymus in growing rats

OBJECTIVES: We studied the effect of a low-quality dietary protein on cellu lar proliferation and maturation in the thymus of growing rats over time. METHODS: After weaning Wistar rats were fed a diet containing 6.5 g/100 g o f corn flour for 6, 10, 18, and 45 d (M groups). For comparison, other rats were fed a diet containing 6.5 g/100 g of casein (Cas groups), and well-no urished age-matched control rats were fed a commercial laboratory diet (C g roups). Food intake, body weight, thymus weight, total number of thymocytes , and the percentages of CD43(+) and Thyl(+) thymocyte phenotypic antigen d eterminants were measured. RESULTS: M versus Cas and C groups showed significant differences (P < 0.01 ) in body and thymus weights after 6 d of feeding, and the total number of thymocytes and the percentages of CD43(+) and Thyl+ were significantly lowe r after 10 d of feeding. The results indicated that consuming a cereal diet for short or long periods causes thymus atrophy in growing rats, with sign ificant reductions in the total number of T-cells concomitant with increase s in the number of immature thymocytes. CONCLUSIONS: The data showed that, in addition to low-protein concentration , low-quality dietary protein is a limiting factor in certain steps of cell ular intrathymic pathways, probably related to the requirement of specific amino acids for optimal immune response. Nutrition 2001;17:724-728. (C) Els evier Science Inc. 2001.