ABSTRACT
The immune system is comprised of organs, structures, cells, and factors that are directly involved in the defense activity of the host against pathogens. The immune system in vertebrates is traditionally divided into innate and adaptive immunity. Adaptive immunity and parts of innate immunity are based on the recognition of nonself molecules or structures that have come in contact with specific receptors on immune cells. The adaptive immune system is comprised of cell-mediated and humoral responses. The most important function of the humoral immune response is the production of soluble molecules, which are synthesized and secreted by the B-lymphocytes. The evolutionary position of reptiles also makes the Reptilia an important group in comparative and evolutionary immunology. Secretions, body fluids, and mucosal surfaces contain several nonadaptive immune compounds effective against invasive microorganisms either in a direct or indirect manner. Interferons are a family of cytokines best known for their antiviral activity.
