Comparison of the protein-binding capacities of cyanogen bromide-activated polysaccharides

Abstract

Techniques for chemically coupling allergens to insoluble polysaccharides have permitted the development of the radioallergosorbent test (RAST) to measure reaginic antibodies. To date these allergens have been those contained in crude commercial allergy extracts. Because these allergens are not well characterised, quantitative measurements of the amounts coupled to the polymers have not been possible. In this study several different polysaccharide polymers were examined for their ability to bind bovine serum albumin (BSA) and ragweed antigen E (AgE) by use of different activation procedures with cyanogen bromide. The capacity of the polymers to bind these antigens was assessed by examining the allergen-particle complex for uptake of radioactivity (BSA) or by measurement of allergen by radioimmunoassay (AgE). Sepharose polymers were the most efficient in binding antigen but tended to trap uncoupled antigen in the gel interstices. Microcrystalline cellulose bound more of both antigens than did Sephadex polymers. The AgE bound to cellulose did not differ immunologically from that of pure AgE IV-C, This suggests that that there was no loss of antigenic determinants during the coupling procedure.