Effects of mold proteases on the biological activity of allergenic pollen extracts.

OBJECTIVE

To determine the effect of mold extracts with high protease activity on the biological activity of allergenic tree, grass, and weed extracts, using in vivo and in vitro methods, in atopic dogs.

ANIMALS

15 dogs with history and clinical signs of atopy. All dogs had strong positive reactions (3+ or 4+) to 1 or more preselected allergens and negative reactions (O) to molds.

PROCEDURE

Mold extracts and saline solution were coincubated separately with tree, grass, and weed pollen extracts at 4 C for 30 and 80 days. Skin end-point titration (30-day incubation) and ELISA inhibition (30- and 180-day incubations) tests were performed on all samples. The biological activity of pollen extracts coincubated with mold extracts was compared with that of pollen extracts coincubated with saline solution.

RESULTS

In the skin end-point titration test, weed pollen extracts coincubated with a mixed mold extract lost a statistically significant amount of biological activity, compared with saline coincubated controls. In the ELISA inhibition test, grass and weed pollen extracts incubated with a mixed mold extract lost a significant amount of biological activity, compared with saline coincubated controls. A significant correlation in the measurement of biological activity was found between a loss of end-point dilution in the skin end-point titration test and a decrease in relative potency, as measured by the ELISA inhibition test for allergenic grass and weed extracts.

CONCLUSION AND CLINICAL RELEVANCE

Mold proteases can decrease the biological activity of certain grass and weed pollen extracts when coincubated in the same vial for 30 days. Separation of mold and pollen extracts, when preparing immunotherapy vaccines, may help prevent loss of pollen extract potency and increase the vaccine's stability and efficacy.