Abstract
The phytohaemagglutinin (PHA) skin-swelling test is widely used in immunoecology and ecotoxicology to estimate cell-mediated immunity presumed to reveal T-cell mediated immunocompetence. To investigate the mechanism triggering this response we have compared in zebra finch (Taeniopygia guttata) the immune responses to two PHA isolectins (PHA-L and PHA-E) differing in their biological properties and one control protein.
This is the first study to show the importance of erythroagglutination in the development of an inflammatory response to PHA-P. Our results indicate that the skin-swelling test using PHA-P reliably mirrors the individual general proinflammatory potential.
The immunological background of the test is highly complex and the test results cannot be interpreted as measurements of the adaptive immunity or T-cell activity. This interpretational change importantly alters our view on the test results regarding the costs of the response or the evolutionary immunological adaptations.