Characterization of allergens from Penicillium oxalicum and P-notatum by immunoblotting and N-terminal amino acid sequence analysis

Background Penicillium species are important causative agents of extrinsic bronchial asthma. However, little is known about the allergens of these ubi quitous fungal species. Objective The object was to analyse the composition, the allergenic cross-r eactivity and the N-terminal sequences of allergens from two prevalent airb orne Penicillium,ll species, P, oxalicum and P. notatum. Methods The allergenic composition and the immunoglobulin (Ig)E cross-react ivity were analysed by immunoblot and immunoblot inhibition, respectively, using sera from asthmatic patients. The N-terminal amino acid sequences of major allergens were determined by Edman degradation. Allergens identified were also characterized by immunoblotting using monoclonal antibody (MoAb) PCM39 against the alkaline serine proteinase major allergen of P. Citrincum . Results Among the 70 asthmatic sera tested, 18 (26%) and 17 (24%) had IgE i mmunoblot reactivity towards components of P. oxalicum and P. notatum, resp ectively. Major allergens (> 80% frequency of IEE-binding) from both specie s are the 33 and 30 E;Da proteins of P. oxalicum and the 34 and 32 kDa prot eins of r. notatum. ISE cross-reactivity among these major allergens and th e 33kDa major allergen of r. citrinum can be detected by immunoblot inhibit ion studies. The N-terminal amino acid sequences of the 34;Da allergen of P . oxalicum and of the 32 and the 28 kDa allergens of r. notatum, share homo logy with sequences of the vacuolar serine proteinase from Aspergillus fumi gatus. The N-terminal amino acid sequence of the 33, kDa allergen of r. not atum Shows sequence homology with that of alkaline serine pl proteinase fro m r. citrinum. Results obtained from immunoblotting showed that MoAb PCM39 reacted with the 34, 30 and 16 kDa IgE-binding components of P. oxalicum, a nd with the 34, 32 and 28 kDa IgE-binding components of r, notatum. Conclusions Results obtained suggest that the 34 kDa major allergen of P, o xalicum, may be a vacuolar serine proteinase. The 33 and the 32 kDa major a llergens of P. notatum may be the alkaline and the vacuolar serine proteina ses of P. notatum, respectively. The 30 and 16 kDa IEE-binding components o f P. oxalicum and the 38 kDa IgE-binding component of P. notatum may be bre akdown products of the 34 and the 32 kDa major vacuolar scrine proteinase a llergens of P. oxalicum and P. notatum,il, respectively.