Environmental influences on fatty acid composition of membranes from autoimmune MRL lpr/lpr mice

Abstract

We analyzed fatty acid make up of cells and organs from autoimmune and immunologically normal mice to determine whether intrinsic differences in composition might be associated with an inflammatory phenotype. Macrophages (MØ) isolated from 4–6-week-old MRL lpr/lpr mice were cultured with phorbol ester (PMA), fibroblast growth factor-1 (FGF-1), fibroblast growth factor-2 (FGF-2) and medium control to determine whether these cell signals might induce membrane fatty acid changes. Individual phospholipid analysis showed 8.4- and 5.1-fold increases in phosphatidylcholine arachidonate (20:4) mole % over baseline values following culture with FGF-1 and FGF-2, respectively. Unfractionated analysis on kidney and liver extracts from 4–6 week MRL lpr/lpr, 16–20 week lpr and 12–20 week MRL ±/± mice demonstrated no significant intrastrain fatty acid differences. Higher levels of 20:4 in 4–6 week lpr mice were noted compared to 16–20 week lpr or +/+ mice in kidney, and liver samples ( P < 0.05). It is possible that membrane changes precipitated by microenvironmental cytokine concentrations may contribute to the expression of autoimmune disease in this model.