Alternaria spore and mycelium sensitivity in allergic patients: in vivo and in vitro studies

Extracts from Alternaria spores and mycelia were prepared to evaluate their allergenic potencies in allergic patients. Twelve Alternaria-sensitive patients, with histories of rhinitis or asthma, were submitted to skin prick tests and five of 12 patients received nasal challenges with spores and mycelia. In vitro, the allergenic activity of each extract was determined by RAST, basophil histamine-release and RAST-inhibition. All patients demonstrated skin reactivity to both extracts while skin reactivity to mycelia was higher than that induced by the spore extract (P < .005). Of the 12 patients, 11 had positive mycelia-RAST and 9/12 had positive spore-RAST. It was found that mycelium-IgE antibody levels were higher than spore-IgE antibody levels (P < .005). Nine RAST-positive patients had positive histamine release tests (> 50%) and basophils challenged with mycelia appeared 10-fold more sensitive compared to the spore challenge. In four of five patients subjected to nasal provocation tests, immediate-type rhinitis was elicited either after spore or mycelium challenge. The patients exhibited a higher nasal reactivity with the mycelium challenge than with spores. RAST-inhibition studies demonstrated that mycelial extracts shared common allergens with spore. These results indicated that Alternaria spore and mycelium were potent allergens in allergic patients and there was a variability in the pattern of in vivo and in vitro reactions between the patients for each allergen.