Correlates of cell-mediated immunity in nestling house sparrows

David F. Westneat, Jennifer Weiskittle, Remona Edenfield, Tria B. Kinnard, Joseph P. Poston

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Cell-mediated immunity is an important vertebrate defense against pathogens, but components of this response may vary in quality. Such variation could arise through the effects of ecology on optimal immunocompetence. We used injections of phytohaemagglutinin (PHA) to measure the factors influencing T-cell proliferation in nestling house sparrows (Passer domesticus). Bivariate analyses revealed positive associations with nestling mass and size, but no effect of ectoparasites. The response to PHA was, however, strongly affected by brood identity. A mixed model with brood identity as a random factor and nestling mass, size, number of ectoparasites, parental feeding rate, clutch size, brood size at hatching, and date uncovered significant positive correlations between PHA response and both nestling mass and the brood size at hatching. Because many of these variables are related hierarchically, we used path analysis to explore the relationships in more detail. We found that a nestling immune response was affected by several indirect paths. Brood size at hatch had both positive and negative paths, and date in the season had several indirect negative effects through its effect on brood size and nestling mass. The approach used and the results obtained offer some new ideas for incorporating immune responses into life history theory.

Original languageEnglish
Pages (from-to)17-23
Number of pages7
Issue number1
StatePublished - Sep 2004

Bibliographical note

Funding Information:
Acknowledgements Ian Stewart, Margret I. Hatch, Hannah Shaefer and Katie Chipko assisted with data collection and measurements. Funds for this project were provided by NSF grant IBN9816989 to D.F.W., supplemental funding from the NSF Research Experiences for Undergraduates program to J.W. and R. M.E., and the University of Kentucky. All procedures were approved by the University of Kentucky’s Institutional Animal Care and Use Committee. We thank Victor Apanius, José Tella, and two anonymous reviewers for suggestions that improved the manuscript.


  • Ecological immunology
  • Immunocompetence
  • Parasitism
  • Passer domesticus
  • Phytohaemagglutinin

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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