Lipid and lipid-free total parenteral nutrition: Differential effects on macrophage phagocytosis in rats

Lipid emulsions provided with total parenteral nutrition (TPN) have been as sociated with mononuclear phagocytic system functional changes. The aim of the present investigation was to assess the influence of TPN with added lip id emulsions on macrophage (M phi) phagocytosis. Wistar rats (n = 70) with external jugular vein cannulation were randomized into seven groups. The ra ts received an oral diet or six different isocaloric (1.16 kcal/mL), isonit rogenous (1.5 g/mL), and isolipidic (30% non-protein calories) TPN regimens : (a) an oral diet with intravenous infusion of saline (OS); (b) non-lipid TPN (glucose); (c) TPN with 10% long chain triacylglycerol emulsion (LCT); (d) TPN with 90% LCT and 10% fish oil (FO) emulsion; (e) TPN with 50% LCT a nd 50% FO; (f) TPN with 10% lipid emulsion with 50% medium chain triacylgly cerol (MCT) and 50% LCT; and (g) TPN with 45% MCT, 45% LCT, and 10% FO. Aft er 96 h of TPN or saline infusion, colloidal carbon (Pelikan, Germany) was injected intravenously at 1.0 mL/kg body weight, and the rats were killed a fter 3 h. Liver, spleen, and lung were weighed and prepared by immunohistoc hemistry analyses with the HAM-56 anti-M phi antibody. Under light microsco py, the total M phi number (MT) and the colloidal carbon phagocytic M phi n umber (MP) were established, and the phagocytic index was calculated as MP/ MT x 100. There were no statistical (P < 0.05) differences in liver, spleen , or lung weights among the seven groups in comparison with the OS group. N on-lipid TPN inhibited spleen and lung Mg phagocytosis when compared with t he OS and lipid-TPN groups. Lipid TPN supplemented with fish oil emulsion i ncreased total liver and lung M phi number and phagocytosis. These results indicate that TPN supplemented with fish oil increases M phi phagocytosis i n rats. (C) Elsevier Science Inc. 1999.