Con A affinity of rat alpha 1-acid glycoprotein (rAGP): changes during inflammation, dexamethasone or phenobarbital treatment as detected by crossed affino immunoelectrophoresis (CAIE) are not only a reflection of biantennary glycan content

Lectin affinity chromatography

A protocol is described for the preparation of lectin affinity chromatography columns using purified lectins and preactivated matrices. A general method is given for the purification of glycoproteins on immobilized Con A. Methods for immobilizing Con A on CDI agarose, Affi-Gel 15, and carbonyldiimidazole-activated agarose are described.

Changes in serum glycoprotein glycosylation during experimental inflammation in mice are general, unrelated to protein type, and opposite changes in man and rat: studies on mouse serum alpha 1-acid glycoprotein, alpha 1-esterase, and alpha 1-protease inhibitor

Using the method of crossed affinity immunoelectrophoresis with concanavalin A in combination with digital image processing, unrelated serum glycoproteins from normal mice and from mice undergoing an experimentally induced inflammation were analyzed for their carbohydrate-derived microheterogeneity profile. This profile changed in a generalized way in mouse serum samples taken at various time intervals after the initial induction of inflammation. The changes are not related to the acute-phase behavior of the protein itself (be it positive, negative, or nonreacting), and they are opposite to the changes in microheterogeneity profiles reported previously for glycoproteins during the acute phase in human and rat sera. These findings are discussed in the context of the biosynthetic control of glycoprotein glycosylation during the acute-phase response.

Microheterogeneity of alpha 1-acid glycoprotein in healthy elderly subjects: patterns obtained by crossed affino-immunoelectrophoresis

Total serum alpha 1-acid glycoprotein (AGP) concentration and concanavalin A-dependent microheterogeneity were studied in 31 healthy elderly subjects (18 men, 13 women, 71 to 76 yr old). Crossed affino-immunoelectrophoresis (CAIE) revealed three microheterogeneity variants of AGP: non-reactive, weakly reactive and strongly reactive with ConA. Two patterns were found in both elderly men and women, i.e. a normal pattern and one with an increase in the non-reactive form. Mean serum AGP levels in the elderly subjects with slightly higher than in a reference group of younger subjects. The Con A non-reactive form of AGP was increased in 42% of the elderly population. An increase in the non-reactive form of AGP in CAIE should be considered as general expression of chronic inflammation which is of no clinical relevance.

Role of sialic acid residues in crossed immuno-affinoelectrophoresis of alpha 1-proteinase inhibitor

We have investigated the importance of the degree of sialylation when an acute phase glycoprotein, alpha 1-proteinase inhibitor (alpha 1-Pi), was analysed both by affinity chromatography on concanavalin A (Con A)-Sepharose and by crossed immuno-affinoelectrophoresis (CIAE) using Con A in the first dimension. Human alpha 1-Pi was isolated by immunosorption chromatography and then more or less desialylated. On Con A-Sepharose chromatography no significant difference was observed in the percentage of the two fractions (retained or not retained) whatever the degree of desialylation. In contrast by CIAE this degree was largely involved in the separation of the different isoforms obtained in the first dimension.