Effect of long-chain fatty acids in the culture medium on fatty acid composition of WEHI-3 and J774A.1 cells

As a first step in determining the mechanism of action of specific fatty ac ids on immunological function of macrophages, a comparative study of the: e ffect of long-chain polyunsaturated fatty acids (PUFA) in the medium was co nducted in two macrophage cell lines, J774A.1 and WEHI-3. The baseline fatt y-acid profiles of the two cell lines differed in the % distribution of sat urated (SFA) and unsaturated fatty acids (UFA). J774A,1 cells had a higher % of SFA (primarily palmitic acid) than WEHI-3 cells. Conversely, WEHI-3 ce lls had a higher % of UFA (primarily oleic acid) than 5773A.1 cells. Neithe r cell line had detectable amounts of alpha -linolenic acid (ALA) or eicosa pentalnoic acid (EPA). The most abundant polyunsaturated fatty acid in both cells lines was arachidonic acid (AA). The efficiency of transport of fatt y acids from the medium to the macrophages by two delivery vehicles (BSA co mplexes and ethanolic suspensions) was compared. Overall, fatty acids were transported satisfactorily by both delivery systems. Alpha-linolenic acid a nd doscosahexenoic acid (DHA) were transported more efficiently by the etha nolic suspension system. Linoleic acid (LA) was taken up more completely th an ALA, and DHA was taken up more completely than EPA by both cell cultures and delivery systems. A dose-response effect was demonstrated for LA, ALA, EPA and DHA in both J774A.1 and WEHI-3 cells. Addition of polyunsaturated fatty acids (PUFA) to the cell cultures modified the total lipid fatty acid composition of the cells. The presence of ALA in the culture medium result ed in a significant decrease in AA in both cell lines. The omega-3/omega-6 fatty acid ratio (omega -3/omega -6), polyunsaturated/saturated fatty acid ratio (P/S), and unsaturation index (UI) increased directly with the amount of PUFA and omega -3 fatty acid provided in the medium. The results indica te that the macrophage cell lines have similar, but not identical, fatty ac id profiles that may be the result of differences in fatty acid metabolism. These distinctions could in turn produce differences in immunological func tion. The ethanol fatty-acid delivery system, when compared with the fatty acid-BSA complex system, is preferable for measurement of dose-response eff ects, because the cellular fatty acid content increased in proportion to th e amount of fatty acid provided in the medium. Similar dose-response result s were observed in a previous in vivo study using flaxseed, rich in ALA, as a source of PUFA. (C) 2001 Elsevier Science Inc. All rights reserved,