Isolation of IgA1 from human serum by affinity chromatography using an immobilized extract of the albumin gland of Helix pomatia.

An extract of the albumin gland of Helix pomatia was linked to Sepharose-4B and used to prepare IgA from group O human serum; immunoelectrophoresis showed that the preparation was free of IgG and IgM. From studies with specific IgA subclass antisera and by comparison with the activity of jacalin-produced material the Helix pomatia extract was found to be IgA1 specific. The preparation had red cell anti-A, B specificity and was suitable for standardizing and controlling anti-human IgA reagents. Preparations using six different carbohydrates as eluants inhibited the agglutination reaction between anti-human IgA and IgA-coated red cells to varying degrees. The pattern of reactions suggested that N-acetyl glucosamine was the IgA binding site for Helix pomatia; this differed from its blood group A determinant (N-acetyl galactosamine) which was the same as that for the IgA1 reactive component of jacalin.