A radioimmunoassay inhibition test (CARIAT) has been developed to measure human anti-tartrazine IgD and IgE antibodies. Graphical analysis of the data obtained has shown that patients with clinically identified tartrazine hypersensitivity can be distinguished from controls by singular characteristics of their IgD but not their IgE antibody patterns. Clinical diagnoses of tartrazine hypersensitivity correlate with relative levels of serum IgD antibody specific for a soluble conjugate of tartrazine with rabbit serum albumin (TZ-RSA). These tartrazine sensitive patients, however, have lower levels of ‘nonspecific’ IgD than controls, i.e., IgD that reacts with cellulose discs conjugated to phenylsulphonic acid antigenic determinants but does not react with TZ-RSA. Although it is significant that the observations demonstrate an association of raised specific IgD levels in patients relative to controls, the possible presence in controls of IgD antibodies against other tartrazine antigenic determinants which may play a role in ameliorating or preventing allergic responses should be considered.
Anti-tartrazine IgD or IgE antibody was determined by assay of the IgD or IgE binding to paper discs coupled to a tartrazine antigen analog (AP-discs). Each result was compared with the amount of antibody binding if the patient's or control serum was preincubated with a free soluble tartrazine-protein conjugated antigen, before being tested on the discs coupled with antigen (AP-discs). Reduction of the amount of IgD or IgE binding to the disc-coupled antigen, when the sera were preincubated with free soluble antigen, indicated specificity of the antibodies for tartrazine antigenic determinants.
The specificity of the serum anti-tartrazine antibodies assayed appears to be the phenylsulphonic moiety, suggesting that the sensitizing agent responsible need not have been tartrazine but could have been one or more of the many other synthetic environmental chemicals with a sulphonated benzene ring. The results obtained suggest that diagnostic tests may be developed for tartrazine hypersensitivity and for hypersensitivity to other chemicals.