The Influence oí Dietary Protein Concentration and Energy Intake on Mitogen Response and Tumor Growth in Melanoma-Bearing Mice1

The effects of energy deprivation and low or high dietary protein levels upon lymphocyte transformation of spleen cells from syn- geneic tumor-bearing and control mice were studied in a murine model of malignant melanoma. Both T- and B-lymphocyte transformation were sig nificantly stimulated by the presence of a growing melanoma. T-cell re sponses, however, were dependent only upon dietary protein concentrations, not the level of energy intake; whereas, the converse was true for B cells. Moreover, mice fed stock diet had the lowest response to mitogens of all diets tested. Except for mice receiving a 15% casein diet, tumor weights were generally not affected by level of intake or the amount of dietary pro tein. Others have demonstrated that melanoma cells have a greater need for tyrosine or phenylalanine than other tumor cells; thus we hypothesized that lymphocyte transformation may be depressed by relatively low phenyl alanine or tyrosine levels in the diet when protein intakes are limited by either a low dietary concentration, a restricted intake of a diet containing adequate protein, or both. J. Nutr. 109: 353-359, 1979.