Prospects for understanding immune-endocrine interactions in the chicken

Despite occupying the same habitats as mammals, having similar ranges of body mass and longevity, and facing similar pathogen challenges, birds have a different repertoire of organs, cells, molecules and genes of the immune system when compared to mammals. In other words, birds are not "mice with feathers", at least not in terms of their immune systems. Here we discuss differences between immune gene repertoires of birds and mammals, particularly those known to play a role in immune-endocrine interactions in mammals. If we are to begin to understand immune-endocrine interactions in the chicken, we need to understand these repertoires and also the biological function of the proteins encoded by these genes. We also discuss developments in our ability to understand the function of dendritic cells in the chicken; the function of these professional antigen-presenting cells is affected by stress in mammals. With regard to the endocrine system, we describe relevant chicken pituitary-adrenal hormones, and review recent findings on the expression of their receptors, as these receptors play a crucial role in modulating immune-endocrine interactions. Finally, we review the (albeit limited) work that has been carried out to understand immune-endocrine interactions in the chicken in the post-genome era.