Affinity Chromatography for Anti-Glucosylated Adhesin Antibody Purification: Depletion of Nonspecific Anti-Protein Antibodies and Antibody Recovery with Unconventional Elution Solutions

Antibodies from sera of a multiple sclerosis (MS) patient subpopulation preferentially recognize the hyperglucosylated adhesin protein HMW1ct(Glc) of the pathogen Haemophilus influenzae. This protein is the first example of an N-glucosylated native antigen candidate, potentially triggering pathogenic antibodies in MS. Specific antibodies in patients' sera can be isolated exploiting their biospecific interaction with antigens by affinity chromatography. Herein, the proteins HMW1ct and HMW1ct(Glc) were first immobilized on appropriately functionalized supports and further used to purify antibodies directly from MS patients sera. We describe a protocol to obtain an antibody fraction specifically recognizing the glusosylated residues on the HMW1ct(Glc) adhesin protein depleting antibodies to the unglucosylated HMW1ct sequence. Different elution solutions have been tested to recover the purified antibody fraction, strongly bound to the immobilized HMW1ct(Glc) adhesin protein.