A role for alcohol dehydrogenase in the Drosophila immune response?

In a recent study Drosophila larvae were injected with bacterial lipopolysaccharide (LPS) suspended in 1% ethanol and differentially induced protein fractions were identified. The levels of several proteins, including alcohol dehydrogenase (ADH), increased in LPS-treated flies and were labelled as immune response proteins. However, because control larvae were not injected with ethanol alone the identified proteins could represent a response to ethanol. Here, we injected Drosophila larvae with combinations of ethanol and LPS. While ADH activity increased in larvae receiving 1% ethanol, it was not increased after LPS injection. These results suggest that ADH plays no role in the Drosophila immune response, and that other proteins identified in the previous study may instead mediate ethanol tolerance in flies and other organisms.