Effect of dietary fat on lymphocyte proliferation and metabolism

The effect of diets enriched with fat containing different fatty acids on glucose and glutamine metabolism of mesenteric lymph nodes lymphocytes, spleen, and thymus and lymphocyte proliferation was examined. The following fat-rich diets were tested: (1) standard chow (CC); (2) medium chain saturated fatty acids (MS)--coconut fat oil; (3) long chain saturated fatty acids (LS)--cocoa butter; (4) monounsaturated fatty acids (MU)--canola oil (n-9); (5) polyunsaturated fatty acids (PU)--soybean oil (n-6). Of the fat-rich diets tested, MS was the one to present the least pronounced effect. Lymphocyte proliferation was reduced by LS (64 per cent), MU (55 per cent), and PU (60 per cent). Hexokinase activity was enhanced in lymph node lymphocytes by PU (67 per cent), in the spleen by MS (42 per cent), and in the thymus by PU (30 per cent). This enzyme activity was reduced in the spleen (33 per cent) by LS and MU (35 per cent). In the thymus, this enzyme activity was reduced by LS (26 per cent) and MU (13 per cent). Maximal phosphate-dependent glutaminase activity was raised in lymphocytes by MS (70 per cent) and MU (20 per cent). This enzyme activity, however, was decreased in lymphocytes by PU (26 per cent), in the spleen by LS (15 per cent), and in the thymus by MU (44 per cent). Citrate synthase activity was increased in lymphocytes by MU (35 per cent), in the spleen by LS (56 per cent) and MU (68 per cent), and in the thymus by LS (42 per cent). This enzyme activity was decreased in lymphocytes by PU (24 per cent) only. [U-14C]-Glucose decarboxylation was raised by all fat-rich diets; MS (88 per cent). LS (39 per cent), MU (33 per cent), and PU (50 per cent), whereas [U-14C]-glutamine decarboxylation was increased by LS (53 per cent) and MU (55 per cent) and decreased by MS (17 per cent). The results presented indicate that the reduction in lymphocyte proliferation due to LS, LU and PU could well be a consequence of changes in glucose and glutamine metabolism.

Dietary fats alter the activity and expression of glucose-6-phosphate dehydrogenase in rat lymphoid cells and tissues

The effect of diets enriched with fat containing different fatty acids on the activity and expression of the glucose-6-phosphate dehydrogenase (EC 1.1.1.49) of mesenteric lymph nodes lymphocytes and intraperitoneal macrophages was examined. Measurements of the enzyme were also performed using spleen, thymus and liver for comparison. The following fat rich diets containing a variety of fatty acids were used: 1-standard chow (CC); 2-medium chain saturated fatty acids (MS)-coconut fat-oil; 3-long chain saturated fatty acids (LS)-cocoa butter; 4-monounsaturated fatty acids (MU)-canola oil (n-9); 5-polyunsaturated fatty acids (PU)-soybean oil (n-6). Of the fat-rich diets tested, MS had the least effect. The G6PDH activity of lymphocytes was reduced by all the fat-rich diets; 16% for MS, 38% for LS, and 54% for MU. Similarly, the enzyme activity was reduced in macrophages; 35%, 86%, and 73%, for LS, MU, and PU, respectively. In contrast, the fat-rich diets elevated G6PDH activity in the lymphoid organs; by 42% in the spleen due to LS and by 131%, 35%, and 56% in the thymus due to LS, MU, and PU, respectively. Fat-rich diets decreased the activity of G6PDH in liver; 42%, 68%, and 39% for MS, MU, and PU, respectively. Some of the changes in G6PDH activity induced by the fat-rich diets occur through the mechanisms of mRNA abundance.