Diagnosis and immunotherapy of mould allergy. I. Screening for mould allergy.

In order to screen for mould allergy, extracts of five common atmospheric moulds (Cladosporium, Alternaria, Penicillium, Aspergillus and Mucor) from various manufacturers were investigated in 130 patients (5-60 years old) with clinical symptoms indicating possible mould allergy. The patients were screened by skin prick test (SPT) and radioallergosorbent test (RAST). SPT seemed to be more sensitive than RAST as a diagnostic screening procedure (80% positive reactions to one or more species compared to 50%). With a partially purified, standardized preparation of Cladosporium herbarum more positive reactions were obtained than with crude extracts without evidence of any unspecific reactions. The difference between commercial and standardized extracts is most probably a result of a variation of both the biological potency of allergenic determinants and the allergenic composition. A considerable number of negative RAST reactions with standard discs were found in patients with positive skin reactions to partially purified Cladosporium, but RAST seemed to be more sensitive than SPT with the other commercial mould extracts. Based on the screening, a very convincing tendency to IgE-reactivity to other moulds was found in patients reacting to Cladosporium, the most common cause of mould allergy. The results confirm the inadequacy of most mould extracts used in diagnostic procedures and strengthen the value of using standardized extracts.