Involvement of Dietary Nucleotides in T Lymphocyte Function

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Abstract
The effect of diet on immune response and tumor growth has become an area of interest in recent years. For sometime, malnutrition has been recognized as a contributory factor to depressed immune response. T lymphocyte function is severely impaired in a state of protein-calorie malnutrition (1–3). However, cell mediated immunity can be restored by improved nutritional repletion(2–3). The effect of dietary nucleotides on immune function has not been well studied. It has been suggested that rapidly proliferating tissues, particularly lymphoid cells and the intestinal epithelium require purine and pyrimidine compounds supplied by either dietary sources or by the liver (4). Differential metabolism of purine and pyrimidine exists in T and B lymphocytes (5–8). These metabolic differences between lymphocyte populations have important clinical consequences. Severe impairment of cellular and humoral immunity in adenosine deaminase deficiency patients and defective T cell function with purine nucleoside Phosphorylase deficiency is well established (9–10). In the clinical setting of renal transplantation, intravenous hyperalimentation(IVH) has been used to support previously well-nourished patients who develop a systemic illness which precludes adequate oral intake. The serendipitous finding that total nutritional support with hypertonic dextrose and amino acid solutions was frequently associated with amelioration of clinical rejection suggested that IVH may enhance the immunosuppression due to azathioprine therapy necessary for survival of the kidney grafts, despite marked reduction in the doses of azathioprine. Association of recurrent rejection with resumption of regular diet implied that constituents of the normal diet are necessary for restoring normal immune response.