“Polyunsaturated fatty acids, derived from foods, have a special role in the immune system, intensifying the effects of stress (cholesterol newsletter, September, 2005) in killing lymphocytes, and blocking the proliferative response of thymic cells (Rotondo, et aI., 1994). They tend to shift immune functions from cellular immunity to humoral (antibody) immunity, and this pattern predisposes to autoimmunity. They are probably directly toxic to the liver (Ritskes-Hoitinga, 1998). DHA increases the leakiness of the bowel, allowing more endotoxin to enter the circulation (RoigPerez, et al., 2004).” -Ray Peat, PhD
Biochim Biophys Acta. 1994 Sep 8;1223(2):185-94.
Inhibition of cytokine-stimulated thymic lymphocyte proliferation by fatty acids: the role of eicosanoids.
Rotondo D, Earl CR, Laing KJ, Kaimakamis D.
The effect of individual fatty acids on the proliferation of thymic lymphocytes in response to interleukin-1 (IL-1) was investigated. Proliferation was estimated by measuring [3H]thymidine incorporation into the acid insoluble fraction of the thymocytes. A concentration-dependent inhibition (in the range 1-100 microM) in the IL-1-stimulated proliferation was observed with the C20 fatty acids dihomo-gamma-linolenic acid (DGLA), arachidonic acid and eicosapentaenoic acid (EPA). A less pronounced concentration-dependent inhibitory response was observed with the C18 fatty acids linoleic acid, alpha-linolenic acid and gamma-linolenic acid. Palmitic acid and oleic did not have any effect on either basal or IL-1-stimulated proliferation at concentrations up to 100 microM. The potencies of each fatty acid for this effect at a concentration of 100 microM were: arachidonic acid > EPA > or = DGLA > linoleic acid. DGLA, arachidonic acid and EPA also attenuated IL-2-stimulated proliferation. The inhibitory action of these fatty acids was not mediated by conversion to prostaglandins or other eicosanoids as the cyclooxygenase inhibitor, ketoprofen and NDGA did not alter their action. Incubation of thymocytes with radiolabelled DGLA and EPA followed by reverse-phase HPLC analysis revealed that DGLA is predominantly converted to a more polar metabolite which is not PGE1 whereas EPA does not appear to be converted to any other detectable metabolite. The data indicate that the inhibitory actions of fatty acids on cell proliferation do not occur as a result of conversion to other metabolites but may be direct effects. The inhibition of cytokine-stimulated lymphocyte proliferation by unsaturated fatty acids would imply that they may attenuate cell-mediated immune reactions.
Thymocytes are much more easily killed by stress than nerve cells, and they are easy to study. The PUFA kill them by increasing their intracellular calcium. The toxicity of DHA is greater than that of EPA, whose toxicity is greater than the alpha-linoleic acid, and linoleic acid was the most potent (Prasad, et al., 2010)…The process by which excitotoxicity kills cells is probably a foreshadowed version of the aging process. -Ray Peat, PhD
J Cell Physiol. 2010 Nov;225(3):829-36.
Role of calcium and ROS in cell death induced by polyunsaturated fatty acids in murine thymocytes.
Prasad A, Bloom MS, Carpenter DO.
We investigated the mechanisms whereby omega-3 and -6 polyunsaturated fatty acids (PUFAs) cause cell death of mouse thymocytes using flow cytometry, focusing on the respective roles of intracellular calcium concentration, [Ca(2+)](i) and reactive oxygen species (ROS). We applied the C-22, 20, and 18 carbon omega-3 (DHA, EPA, ALA) and omega-6 (DTA, ARA, and LNA) fatty acids to isolated thymocytes and monitored cell death using the DNA-binding dye, propidium iodide. When applied at 20 µM concentration, omega-3 fatty acids killed thymocytes over a period of 1 h with a potency of DHA > EPA > ALA. The omega-6 PUFAs were more potent. The C18 omega-6 fatty acid, LNA, was the most potent, followed by DHA and ARA. Cell death was always accompanied by an increase in the levels of [Ca(2+)](i) and ROS. Both increases were in proportion to the potency of the PUFAs in inducing cell death. Removing extracellular calcium did not prevent the elevation in [Ca(2+)](i) nor cell death. However, the intracellular calcium chelator, BAPTA, almost totally reduced both the elevation in [Ca(2+)](i) and cell death, while vitamin E reduced the elevation in ROS and cell death. BAPTA also prevented the elevation in ROS, but vitamin E did not prevent the elevation in [Ca(2+)](i). Thapsigargin, which depletes endoplasmic reticulum calcium, blocked the elevation in [Ca(2+)](i), but CCCP, a mitochondrial calcium uptake inhibitor, did not. These results suggest that the six PUFAs we studied kill thymocytes by causing release of calcium from endoplasmic reticulum, which causes release of ROS from mitochondria which leads to cell death.
