Bovine plasma posses abundant phospholipids binding Ig M

GIMENEZ G; NOSEDA DIEGO GABRIEL; FLORIN CHRISTENSEN J

Puerto Iguazu. Misiones

Congreso; Reunion Anual de la Sociedad Argentina de Investigaciones Bioquimicas; 2004

Sociedad Argentina de Investigaciones Bioquímicas

Ruminants are a particular zoological group in that their erythrocytes lack phosphatidylcholine (PC), possess abundant sphingomyelin (SM) and their phosphatidylethanolamine (PE) contents is about ten times lower than in human erythrocytes. Less than 2% of PE is exposed in the cell surface. We found that bovine plasma lyses erythrocytes of other species including the closest non ruminant artiodactyl, the pig. Several lines of evidence indicate that the relevant antigens are phospholipids. Absorption with SM/PE but not with pure SM liposomes, abrogates hemolysis. The hemolytic effect is complement dependent. Immunoblots show that SM/PE liposomes bind about the double amount of IgM than pure SM liposomes, suggesting that an unspecific binding to the liposomes is not likely to account for the differences observed with the different lipid compositions. The antibodies can be eluted from the liposomes by simple treatment with Phospholipasc C, indicating the relevance of the integrity of the phospholipid molecule in the process. Similar experiments using anti bovine IgG-HRP revealed no activity. Therefore this newly described system can be considered an innate physiological mechanism. It might he particularly developed in ruminants, and not in other taxa, as a means to ward off any invasive activity from the abundant ruminal microbes that thrive in their particularly large stomachs, that characterized them.