We have investigated the importance of the degree of sialylation when an acute phase glycoprotein, α1-proteinase inhibitor (α1-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 α1-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.
