Influence of dietary fat concentration and saturation on immune ontogeny in mice.

Dietary fat modulation of immune responsiveness was studied using a murine model subjected to prenatal and postnatal dietary manipulation. The weight of lymphoid associated organs, particularly the spleen, thymus and liver were significantly influenced by dietary fat saturation and concentration whereas other organs studied were not influenced by this manipulation. The serum immunoglobulins IgG1 and IgG2, but not IgM or IgA, increased in mice fed the polyunsaturated fat (PUF) diet as compared to the levels in those mice fed the saturated fat (SF) diet. While dietary manipulation generally did not influence the peripheral differential blood cell counts, the percentage of immunoglobulin positive splenic cells changed with dietary manipulation; the percentage of T cells, however, was not influenced by the experimental diets. In contrast, T-cell blastogenesis was influenced by both saturation and concentration of dietary fat whereas B-cell transformation was influenced by neither variable. Changes in T-cell responses were manifested through changes in the lymphocytes, and not cell numbers; PUF, particularly high levels, suppresses lymphocyte blastogenesis whereas low levels or a deficiency of PUF intensify this response. It is concluded that dietary fats influence the modulation and level of immune function.

Effects of low dietary protein concentration and energy deprivation on lymphocyte transformation in melanoma-bearing mice.

Temporal changes in lymphocyte blastogenesis were studied using spleen cells from syngeneic melanoma-bearing and control mice fed various levels of purified diets containing 6, 10 or 30% casein. T-cell blastogenesis was stimulated by the presence of the tumor and these responses changed with the duration of feeding. In addition, protein concentration did not affect T-cell transformation but the level of energy intake influenced concanavalin A induced DNA synthesis. In contrast, the growing melanoma did not influence B-cell transformation whereas a very low level of dietary protein, a low level of energy intake and duration of the dietary manipulation influenced these cells. Tumor weights were generally not affected by the diet except in mice receiving a very low level of energy intake. Thus, we have found that B-cell responses were affected more than those of T-cells and that moderate protein deficiency did not enhance cellular immune responses in syngeneic tumor-bearing and control mice.