Bovine erythrocytes anomalies link to anti-phospholipid antibodies

GIMENEZ G.,; BELAUNZARÁN M.L.,; ISOLA E.L.D.,; FLORIN-CHRISTENSEN J.

Noordwijkerhout, Holanda.

Congreso; FEBS Special Meeting European Lipidomics Initiative.; 2006

FEBS

Erythrocytes of bovines and other ruminants have a strikingly anomalous phospholipid composition, with low or absent phosphatidylcholine (PC), the phosphatidylethanolamine (PE) confined to the inner leaflet, together with a high sphingomyelin (SM) content, and the unique occurrence of a derivative of PE, N-acyl-PE (NAPE). In contrast, non-ruminant artiodactylans, like the pig, contain relatively high PC levels. In addition, like in other mammals, bovine plasma lipoproteins contain low levels of PE. The biological explanation of this phenomenon has remained elusive. Here, we report in normal bovine serum, the regular presence of high levels of anti-phospholipid antibodies of IgM isotype against PE, aminoethylphosphonolipid (AEPL), the phosphono analogue of PE formed by rumen ciliates, and to a lesser extent against PC. No antibodies were detected against SM or NAPE, the major components of bovine erythrocytes. The techniques used included: ELISA, Dot blots and Immunoblots. We additionally found that treatment with bromelain, which turns mice erythrocytes sensitive to their characteristic anti-PC antibodies, did not result in the hemolysis of bovine erythrocytes exposed to their own serum. These results indicate that lipid composition, rather than masking by glycocalix proteins like in mice, is the mechanism accounting for resistance of bovine erythrocytes to self antibodies. What is the origin of the anti-phospholipid antibodies? We propose that the presence of AEPL from ruminal ciliates in the bovine bloodstream induces the generation of anti-phospholipid antibodies, and that the unique phospholipid composition of ruminant erythrocytes, along with the low PE content in plasma lipoproteins, appears as an evolutionary adaptation to tolerate otherwise cytolytic antibodies. The ruminant mode of life with its concomitant ciliate fauna is hereby linked to the peculiar conformation of the erythrocyte membranes of this group of mammals.