affinity chromatography matrix has reduced density of ligands

The invention relates to an affinity chromatography matrix, in the form of gel, comprising polymer particles having at least one oligosaccharide corresponding to a blood group A epitope and / or blood group B is grafted, via a spacer, characterized in that the oligosaccharide density is between 0.2 and 0.7 mg / ml matrix. The invention also relates to uses of this matrix to prepare therapeutic use of immunoglobulin concentrates.