Experimental assessment of the allergenicity of a psyllium-containing laxative

The allergenicity of psyllium was investigated using the Guinea Pig Maximation Test. Four of 12 animals gave positive skin reactions. Subsequent inhalation challenge of the same animals yielded respiratory hypersensitivity reactions in four of the animals. Two animals gave both skin and respiratory responses. The mosaic of respiratory and dermatologic symptoms demonstrated by animals resembled the pattern of findings reported in clinical studies. Results of SDS-acrylamide gel electrophoresis, immunoblot and protein determinations of aqueous psyllium extracts failed to indicate the presence of protein. Spectrophotometric studies suggested that the extract was a gum with a molecular weight greater than 14,000 daltons.