DELAYED AND IMMEDIATE ALLERGY CAUSED BY METHYLHEXAHYDROPHTHALIC ANHYDRIDE

Epoxy resin compounds (ERC) include a large number of chemicals, such as epoxy resins (ER), reactive diluents and hardeners. Many hardeners, e.g., aliphatic polyamines, are well-known sensitizers. Another type of ER hardeners are the phthalic anhydrides, such as methylhexahydroph thalic anhydride (MHHPA) and methyltetrahydrophthalic anhydride (MTHPA ), which have been reported as causing immunologically-mediated respir atory diseases and contact urticaria, but not allergic contact dermati tis. Here, we present a horizontal boring-machine worker who developed allergic contact dermatitis, as well as allergic rhinitis and an imme diate contact skin reaction from MHHPA. Patch testing with a dilution series of MHHPA in pet. elicited the following results: 2%, 1% and 0.5 %, ++; 0.25% and 0.125%. + (3- to 6-day readings). An immunohistochemi cal and electron microscopic study also indicated that the patch test reactions were conventional-delayed allergic reactions. Interleukin 8 was observed in the epidermal cells, whereas interleukin 4 immunoreact ivity was detected in the dermal cells. Immunoreactivity to interleuki n 5, granulocyte/macrophage-colophony stimulating factor (GM-CSF) or e osinophil cationic protein was not seen. In conclusion, the patient de veloped both Type I and Type IV allergy to MHHPA. The clinical data, p atch test results, immunohistochemical and electron microscopic observ ations indicated that the MHHPA allergy detected by the patch test rea ction was a conventional delayed-type hypersensitivity reaction. The p atient also had an allergic patch test reaction to para-phenylenediami ne and diaminodiphenylmethane, possibly representing occupational sens itization. (C) Munksgaard, 1997.