P1.149 Wednesday, Jan. 4 Ontogeny of constitutive innate immune function in free-living altricial house sparrow nestlings KILLPACK, TL*; OGUCHI, Y; KARASOV, WH; Univ. of Wisconsin-Madison; Univ. of Wisconsin-Madison; Univ. of Wisconsin-Madison email@example.com
Some developmental studies in mammals and birds suggest that juveniles depend primarily on innate immune defenses during the growth period, given that adaptive defenses require weeks to generate cells with antigen-specific receptors. Studies of ontogenetic changes in altricial birds, which undergo rapid development post-hatch, have been few until relatively recently. We hypothesized that altricial house sparrows rapidly develop constitutive, innate immune function during the nestling period, and that function reaches adult levels prior to fledging (~15 days post-hatch (d) in house sparrows). We collected nestlings at 3, 6, 9, or 12 d. Body mass and skeletal lengths were measured and blood samples were taken for hematocrit and for analysis of 3 measures: natural antibody-mediated agglutination, complement-mediated lysis, and bacterial killing activity of lysozyme. Adults were sampled for comparison to nestlings. Body mass and tarsus length of nestlings increased with age, reaching adult levels by 9d, and hematocrit reached adult levels by 12d. We observed no significant increase in agglutination from 3d to 12d, while lysis activity gradually increased from 3d to 12d. Agglutination and lysis at 12d were at least 60% lower than adult levels. Lysozyme results and details of assay optimization will be reported. From the assays performed thus far, we conclude that constitutive innate immune function does not follow the rapid developmental patterns of other structural and physiological measures in house sparrows. Further, given that constitutive innate immune function is still at sub-adult level at the end of the nestling period, altricial fledglings may be more vulnerable to infection than adults. Support: NSF-GRF, USDA-Hatch, AOU.