Interest in interleukin-1 (IL-1) has increased dramatically over the last decade, but has been largely restricted to immunologists, cell biologists and those studying inflammation and cancer. However, it has recently been recognized that the brain directly controls or modulates many aspects of immune function, while molecules classically associated with the immune system, such as interleukin-1, are synthesised within the brain and act directly on the central nervous system to modify local and systemic functions. Thus, this topic is relatively new to neurobiologists, and this book is the first comprehensive description of current knowledge on interleukin-1 in the brain, including its location, synthesis and receptors, actions on behaviour, fever, metabolism, neuroendocrine function, electrical activity of the brain, nerve growth factor, and relationship to clinical indications. The book is organised into three sections. The first reviews the data available on the neural localisation of IL-1 and the nature of its central receptors. The main part of the book examines the different neural effects of IL-1 and the mechanisms which are involved in these actions, comparing IL-1 where possible to other inflammatory cytokines which also have neurotrophic effects. The final section evaluates the possible role of IL-1 in neural plasticity and neuronal degeneration.