UNDERSTANDING IMMUNOLOGY IN DISEASE DEVELOPMENT AND CONTROL

Two functional aspects of the avian immune system, the humoral and the cell-mediated arms, provide the basis for the preventive and protecti ve response against disease-causing microorganisms. On the other hand, certain avian diseases may induce a transient or permanent immunosupp ressive state in one or both of these arms, leading to increased disea se susceptibility. In addition to the classical immune response, manif est-ed as antibody production or effector cell activation, several cyt okines and metabolites are also produced. The consequence of cytokine- and metabolite-mediated microenvironments may be either beneficial or result in a noninfectious immunopathology. Nevertheless, the integrit y of the immune system and its functional modulation by factors such a s genetics, nutrition, and prophylactic approaches continue to be an i mportant focus of attention in current poultry research and production efforts.