Inflammation-induced expression of sialyl Lewisx is not restricted to α1-acid glycoprotein but also occurs to a lesser extent on α1-antichymotrypsin and haptoglobin

Acute and chronic inflammation-induced expression of sialyl Lewis(x) has already been shown to occur on alpha(1)-acid glycoprotein. We now demonstrate that this phenomenon is not restricted to alpha(1)-acid glycoprotein but also occurs on two other x acute-phase proteins. ie on alpha(1)-antichymotrypsin and on haptoglobin. The level of expression of sialyl Lewis(x) on these proteins was lower than on alpha(1)-acid glycoprotein, in all likelihood because alpha(1)-acid glycoprotein is the only acute-phase protein containing tetraantennary glycans. No expression of sialyl Lewis(x) was detectable on alpha(1)-protease inhibitor, a protein x with a high diantennary glycan content. Non-sialylated Lewis(x) was not detectable on these major acute-phase proteins in any of the conditions studied. This indicates that the majority of the alpha 3-linked fucose residues are present as sialyl Lewis(x) on alpha(1)-acid glycoprotein, alpha(1)-antichymotrypsin and haptoglobin. The absolute contribution to the total phenotype in plasma of protein containing this determinant in a multivalent form was highest for alpha(1)-acid glycoprotein. This leads us to propose that alpha(1)-acid glycoprotein is, among the acute-phase proteins studied, the one with the highest potential for interference with the extravasation of leukocytes by binding to the selectins.