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The number of bound sheep red blood cells (SRBC) per lymphocyte of 16 healthy subjects were assayed prior and after addition of unsaturated fatty acids. Addition of fatty acids to the assay system was found to increase significantly the number of avid T lymphocytes (which bind more than 10 SRBC). It is suggested that increased fatty acid level might change lipid fluidity of the plasma membrane and increase the number of attachment points between the cell surface of the lymphocyte and SRBC. The immuno-regulatory effect of fatty acids is discussed.

Oxidative stress is defined as an imbalance between prooxidants and antioxidants. There is a need for a simple in vitro method for evaluation of the effects of oxidative stress and the effects of antioxidants. In the present study, we used primary cultures of human lymphocytes exposed to either paraquat (PQ) or mitomycin C., two prooxidants generating two different types of free-radicals formed either by P450-reductase or by DT-diaphorase, respectively. The toxicity was measured by estimation of DT-diaphorase and glutathione peroxidase (GSH-Px) activity, and by estimation of the level of malondialdehyde (MDA) as a function of time and increasing doses of the two prooxidants. The enzyme activities were related to both total DNA content and total protein content of cellular homogenate. All estimations were made by exposing human lymphocytes to increasing concentrations (up to 100μM) of the two prooxidants. However, since cellular death occurred at concentrations above 60μM, only data for exposure to concentrations below 70μM are presented. When the enzyme activities were expressed per cellular unit (i.e. per gram DNA) 30μM mitomycin C induced a 30% increase in DT-diaphorase activity. Similarly, a dose-dependent increase (maximum 100% increase) in DT-diaphorase activity was found after exposure to PQ (up to 60μM). Similar data were obtained when data were related to the total protein. Only a minor increase (11%) in GSH-Px activity was induced by 50μM mitomycin C., whereas 20-70μM PQ induced a 41% increase in GSH-Px activity. Both prooxidants induced more than a doubling in the cellular MDA concentration. These findings demonstrate that both DT-diaphorase and GSH-Px are up-regulated during oxidative stress. However, sensitivity to prooxidant-induced stress seems to depend to some extent on the chemistry of the free-radicals generated. Thus, the single-electron pyridium cations generated by PQ seem to be more toxic than the single-electron semi-quinones generated by mitomycin C. The same cellular system was used to evaluate the effects of antioxidants. Quercetin, a naturally occuring flavone, and selenium (sodium selenite), which is an essential part of glutathione peroxidase, were selected. PQ-induced stress and exposure to 5μg/ml quercetin for 4 hours decreased the MDA level in the medium by 11% and in the cells by 33%. PQ-induced stress and exposure to 160μg/l selenium for 18 hours reduced MDA levels similarly, by 19% in the medium and 14% in the cells. Both antioxidants induced a 50% reduction in GSH-Px activity.

The fatty acid pattern of muscle and fat tissue of the arctic seal, birds and mammals are presented and compared with the fatty acid pattern of the corresponding tissues of domestic animals normally used as meat sources in western countries. The triglyceride content of muscle samples were also assayed in these animals. A gas chromatography-mass spectrometry system was used for the localization of the position of double bonds in the unsaturated acids using their pyrrolidides. The data indicated that the fat tissue from the seal is the major source of polyenoic acids i. e., tri-and pentaenoic acids in the diet of the arctic hunter. These acids are derived metabolically from linolenic acid. In contrast polyenoic acids i. e. linoleic acid and its derivatives in the non-arctic diet are mainly supplied from muscle tissue of non-ruminant animals as well from the sources of vegetable origin. The fat content of muscle tissue in arctic animals was not lower than that of domestic meat. The data presented are related to recent studies of the apparent low incidence of coronary heart diseases in arctic populations.

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