A comparison of the lipid composition of peripheral blood cells and head kidney leucocytes of Atlantic salmon ( Salmo salar L.)

Abstract

Analysis of lipid composition of peripheral blood cells (PBL) and head kidney leucocytes of Atlantic salmon parr revealed marked differences in lipid content, lipid class composition and fatty acid composition. Leucocytes had a higher lipid content and higher levels of neutral lipid, particularly triacylglycerols (TAG) within their lipid, than erythrocytes. The total lipid of the erythrocytes was rich in (n-3) polyunsaturated fatty acids (PUFA) (54.3% of total fatty acids), especially 22:6(n-3) (43.5%), whereas the lipid of leucocytes had notably higher proportions of 18:1(n-9) than that of the erythrocytes. The overall content of (n-6) PUFA was also higher in the lipid of leucocytes than in that of the erythrocytes [7.4 vs. 4.1%]. The phosphatidylethanolamine (PE) fraction of both cell types contained the highest level of (n-3) PUFA of the lipid classes examined. Phosphatidylcholine (PC) was rich in 16:0, whilst phosphatidylserine (PS) had high levels of both 16:0 and 18:0, as did phosphatidylinositol (PI). The latter phospholipid contained around 13.6% 20:4(n-6) in both cell types. The lipid of head kidney macrophages from the Atlantic salmon was richer in phospholipids than that of leucocytes and T- and B-cells from the same tissue. No marked differences were observed between macrophages, T- and B-cells in terms of total lipid fatty acid composition.