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THE PESTICIDE METARHIZIUM ANISOPLIAE HAS AN ADJUVANT EFFECT ON THE ALLERGIC RESPONSE TO OVALBUMIN IN MICE
Instanes, C., MDW Ward, E. Groeng, AND G. Hetland. THE PESTICIDE METARHIZIUM ANISOPLIAE HAS AN ADJUVANT EFFECT ON THE ALLERGIC RESPONSE TO OVALBUMIN IN MICE. Presented at Society of Toxicology 42nd Annual Meeting, Salt Lake City, Utah, March 9-13, 2003.
Metarhizium anisopliae is a parasitic fungus employed as a biological control agent against vermin and used in the US for indoor control of cockroaches. Sensitization to cockroach allergens is associated with development of asthma. This pesticide is non-pathogenic for humans and is therefore an alternative to more toxic chemicals. However, in previous studies M. anisopliae has been shown to cause allergic and asthma-like responses in mice. We examined the adjuvant activity of M. anisopliae crude antigen (MACA), consisting of different parts of the fungus including mycelium, and mycelium alone, on the response to the model allergen ovalbumin (OVA) in the poplietal lymph node assay (PLNA). Groups of 8 mice were injected with MACA + OVA, mycelium + OVA, MACA, mycelium or OVA alone in the right hind footpad. On day 21 the animals were boosted with OVA and then exsanguinated and the PLN removed on day 26. The levels of OVA-specific serum IgE and IgG1 (Th2 immune response), and IgG2a (Th1 immune response) were determined by ELISAs. There was a statistically significant increase in the levels of anti-OVA IgE and IgG1, but not anti-OVA IgG2a in the group given mycelium + OVA compared with OVA alone. In the group given MACA (1/5 of concentration for mycelium) + OVA the levels of anti-OVA IgG1 increased in one out of two experiments. Moreover, both MACA and mycelium + OVA compared with OVA alone induced increased weight and cell number of the excised PLN. Our study shows that exposure to M. anisopliae together with OVA results in an increased local inflammatory response and Th2-dependent immune response to a model allergen in mice. This indicates that M. anisopliae has the ability to increase an allergic response to allergens in the environment. In particular, use of this pesticide for cockroach control in homes, may result in an enhanced allergic reactions in individuals who are sensitized to cockroach allergens. (This abstract does not reflect EPA policy.)