Variability of extracts used in immunoprecipitin tests.

Immunodiffusion reactions of several different commercial fungal extracts from organisms were compared to those obtained from patients' environments. Sera were obtained from patients suspected of having hypersensitivity lung disease (HLD). There was a difference in reactivity among the sources of the antigen and in some lots of antigen from the same commercial supplier. The results demonstrate a wide variation in the reactivity of different antigenic extracts and emphasize the need for uniform standardization of preparations used in precipitin tests.