Human Antihapten Antibodies in Trimellitic Anhydride Inhalation Reactions

Abstract

Inhalational exposure to trimellitic anhydride (TMA) produces an immediate-type asthmatic or a late respiratory systemic syndrome in certain workers after a latent period of work exposure. TMA has been found to react with proteins to produce a hapten-protein complex (trimellitate [TM] protein) or become hydrolyzed in aqueous, alkaline solutions to produce a salt, NaTM. Using a solid-phase radioimmunoassay technique, antibodies of different Ig classes were detected against TM-protein conjugates. IgE antibody was detected in three of five workers with asthma. IgG and IgA antibodies were detected in most exposed workers but higher levels of antibody were found in symptomatic workers even after long periods without direct TMA exposure. IgM antibody activity against TM-human serum albumin (TM-HSA) was detected but did not differentiate symptomatic from asymptomatic workers. NaTM served as a hapten for study because it does not react with proteins to form a hapten-protein complex as TMA does. The NaTM only partially inhibited IgG antibody activity against TM-HSA and much smaller amounts of TM-HSA than of NaTM were required to neutralize IgG antibody. A similar result was found with TM-ovalbumin. The latter results suggest that some IgG antibody is directed against a TM-protein moiety, probably a TM-amino acid determinant. In contrast to IgG, marked inhibition by NaTM of IgA and IgM antibody against TM-HSA was found in the sera studied.