ABSTRACT
This chapter focuses on two broad areas of emphasis: first, a description of the interleukin-1 (IL-1) family of peptides, their receptors, and their biological activities that are related to host defense; second, an overview of the production of IL-1 and its biological activities in species of veterinary importance. Unlike IL-1 receptors on murine or human fibroblasts and neutrophils, it appears that the molecular sizes of IL-1 receptors on these types of bovine cells are indistinguishable from one another by affinity crosslinking analysis. What is refered to as the IL-1 receptor antagonist (IL-Ira), was originally described as a protein released by human monocytes stimulated with IgG complexes that blocked IL-1-induced murine thymocyte proliferation, collagenase production by rabbit articular chondrocytes, and prostaglandin E 2 production by human fibroblasts. Although the beneficial effects of IL-1 in host defense are impressive, they are typically observed only when the IL-1 is given, or its production is blocked, at the time the infection is initiated.
