Airborne viable fungi in Riyadh and allergenic response of their extracts.

The allergenicity and antigenicity of various airborne fungi isolated from the atmosphere of Riyadh were studied. Protein nitrogen contents were estimated and found to range from 0.9 mg ml(-1) for Cladosporium to 2.1 mg ml for Aspergillus extracts. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis for those extracts exhibited a number of protein bands of higher molecular weight between 13 and 80 kDa for Alternaria, Ulocladium, Penicillium, Aspergillus and Cladosporium. Extracts in both aqueous and lyophilized forms were sterilized and tested for diagnostic skin prick test in 100 consecutive patients having bronchial asthma and allergic rhinitis. Overall, 13% of patients reacted positively to fungal extracts, revealing allergic sensitization to these fungi. These findings necessitate further investigation as regards the purification and characterization of these local extracts for better diagnostic use in patients in Saudi Arabia.