The aging of the immune response in Drosophila melanogaster.

Senescence of functional immunity in invertebrates has been a topic of recent interest. Results from previous studies have been inconsistent with older adults exhibiting wide variation in response to infection. In the present study, we assayed the senescence of functional immune response using a large outbred population of Drososphila melanogaster as the model host and Serratia marcescens as the model pathogen. We assessed the effect of an individual's age, parental age, sex, and mating status on overall antibacterial immunity. We found an improvement of immunity with the progression of age with 13-day-old flies exhibiting lower bacterial load compared with 3-day-old flies. Parental age did not show consistent effects on the antibacterial immunity of the offspring. Neither mating status nor the sex of an individual had any significant effect on immune response.