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 lymphoc ytes, spleen, and thymus and lymphocyte proliferation was examined. Th e following fat-rich diets were tested: (1) standard chow (CC); (2) me dium chain saturated fatty acids (MS) - coconut fat oil; (3) long chai n 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 pr esent the least pronounced effect. Lymphocyte proliferation was reduce d by LS (64 per cent), MU (55 per cent), and PU (60 per cent). Hexokin ase 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 redu ced by LS (26 per cent) and MU (13 per cent). Maximal phosphate-depend ent 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), a nd in the thymus by MU (44 per cent). Citrate synthase activity was in creased in lymphocytes by MU (35 per cent), in the spleen by LS (56 pe r cent) and MU (68 per cent), and in the thymus by LS (42 per cent). T his enzyme activity was decreased in lymphocytes by PU (24 per cent) o nly. [U-C-14]-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-C-14]-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 proli feration due to LS, LU and PU could well be a consequence of changes i n glucose and glutamine metabolism. (C) 1998 John Wiley & Sons, Ltd.