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