Preparation and Immunological Properties of a Brilliant Blue-Protein Conjugate

Brilliant Blue F.C.F. (BB), after purification to remove high molecular weight, blue-colored contaminants present in commercial preparations, was conjugated to bovine serum albumin (BSA). Phosphorus oxychloride was used to transform the sulfonate groups of BB to sulfonyl chloride groups; the product of this reaction was then allowed to react further with the protein. The conjugate thus prepared was purified by Sephadex G-25 column chromatography and found to contain 7 moles of BB per mole of BSA. Immunological studies in the rat indicated that neither IgE nor IgG_a antibodies to BB could be detected in the sera of immunized animals. This would tend to suggest that BB possesses a low degree of allergenicity. However the possibility that some individuals under appropriate circumstances could respond with allergic manifestations to BB cannot be dismissed.