ALLERGIC RESPONSES TO THE BIOPESTICIDE METARHIZIUM-ANISOPLIAE IN BALBC MICE/

Metarhizium anisopliae is used as a microbial pesticide to control coc kroaches and other insects. M. anisopliae has demonstrated neither inf ectivity nor toxicity in mammals, However, allergenicity has not been assessed. ill. anisopliae is a prototype for other organisms released into the environment for pesticide or other beneficial applications. H ence this study is part of an effort to develop methods for screening such organisms for allergenic potential. Soluble factors from fungal c omponents were combined in equal protein amounts to form a crude funga l antigen (MACA). Balb/c mice were intratracheally (IT) challenged wit h 25 mu g fungal antigen 13 days post intraperitoneal sensitization wi th the fungal antigen in alhydrogel adjuvant. Additionally, mice were sensitized with adjuvant alone or chitin media in adjuvant as experime ntal controls. Serum and bronchoalveolar lavage fluid (BALF) were harv ested prior to challenge and at 1 and 7 days post IT challenge (DPIT). These mice exhibited immune and pulmonary inflammatory responses to M ACA characteristic of allergy. Total serum IgE for antigen-sensitized animals increased 7.6-and 14.7-fold over that for chitin media and adj uvant controls, respectively, at 7 DPIT. Less striking increases were seen at 24 DPIT and prior to challenge. BALF IL-4 was dramatically ele vated only in MACA-sensitized and challenged mice and only at 1 DPIT. Additionally, there was a dose-dependent increase in BALF eosinophils from MACA-sensitized mice at both 1 and 7 DPIT. While lymphocyte count s were increased for all treatment groups at 1 DPIT, by 7 DPIT lymphoc yte counts for MACA-sensitized mice only were significantly elevated c ompared to controls. Pulmonary inflammation, edema, and cell damage we re apparent at 1 DPIT (25 mu g MACA), as indicated by a neutrophilic i nflux and elevated levels of total protein and LDH, in both sensitized and control groups. These effects were significantly decreased, but n ot eliminated by reduction of the challenge dose to either 10 or 5 mu g MACA. While BALF IL-4 was also reduced at the lower challenge doses, eosinophilia and total IgE were unchanged. The data suggest that the crude fungal extract MACA contains one or more potent allergens and th at total IgE may be useful in the identification of the allergen(s). ( C) 1998 Society of Toxicology.