FATTY-ACID OXIDATION IN LYMPHOCYTES FROM WALKER-256 TUMOR-BEARING RATS

The oxidation of fatty acids in lymphocytes from the mesenteric lymph nodes of Walker 256 carcinosarcoma-bearing rats (TB) was studied, as w ell as the activity of the mitochondrial long-chain fatty acid transpo rt system. Two-month old Wistar rats were subcutaneously implanted wit h 10(7) cells and after 2 weeks the tumor mass was 15-20% of the carca ss weight. The activity of carnitine palmitoyltransferase (CPT) II was demonstrable in the lymphocytes of the TB group (8.2 +/- 5.6 nmol/min per mg mitochondria protein for 15 rats) and was not detected in the control, while that of CPT I was only slightly increased in the former . Similar rates of [1-C-14]-palmitate decarboxylation were found for T B and control rat lymphocytes. However, when the rate of decarboxylati on of [1-C-14]-palmitate present in the intracellular pool of lipids w as investigated in cultured lymphocytes, the cells of TB rats exhibite d rates 17-fold higher than those of control animals in the presence o f fetal calf serum (FCS). Decarboxylation in the presence of TB rat se rum was 178-fold higher than obtained with normal rat serum, and 1.4-f old compared to FCS. These results suggest that, during cachexia, lymp hocytes preferably oxidize intracellular lipids, and that this capacit y is greatly enhanced by factors circulating in the serum of tumor-bea ring rats.