Variations in the relative proportions of microheterogeneous forms of plasma glycoproteins in pregnancy and disease

Abstract

Using lectin affinity crossed immunoelectrophoresis with concanavalin A in the first dimension and electroendosmotic elution with sugar in the second dimension, the microheterogeneity of a range of plasma proteins was examined. Of the five chosen proteins, alpha 1-protease inhibitor and caeruloplasmin displayed complex patterns, with more than four components. Alpha 1-Antichymotrypsin was composed of three or four components whilst alpha 1-acid glycoprotein and alpha 2-HS glycoprotein displayed two, three or four components. The number of components seen in these proteins depended on the serum sample origin. In pregnancy and in patients receiving exogenous aestrogen the relative proportions of the components of all five proteins were altered in the direction of less con A binding; however alpha 1-acid glycoprotein and alpha 1-antichymotrypsin showed the greater change. In acute disorders the proportions of protein components of alpha 1-antichymotrypsin and alpha 1-acid glycoprotein were altered towards a higher level of con A binding components. There is no significant alteration in con A binding associated with the chronic inflammatory response to cancer and rheumatoid arthritis. There was a general reduction of con A binding in all five plasma proteins in conditions when there was a high blood aestrogen level. This decreased affinity for con A was independent of the overall effect of the aestrogen on the serum concentration of the plasma protein. These results suggest that the glycosylation of plasma proteins is probably under the same regulatory system.