Description
Monocytes are the main source of secreted IL1. They express predominantly IL1- beta while human keratinocytes express large amounts of IL1-alpha. Murine macrophages display a transition from IL1-beta to IL1-alpha production during maturation of monocytes into inflammatory macrophages.There are two functionally almost equivalent forms of IL1, IL1-alpha and IL1-beta that are encoded by two different genes. IL1-beta is the predominant form in humans while it is IL1-alpha in mice. Both forms of IL1 bind to the same receptor and therefore also show similar if not identical biological activities. The IL1-beta but not the IL1-alpha precursor must be processed before it can bind to the receptor. Both forms of IL1 bind to the same receptor and therefore also show similar if not identical biological activities. The receptor isolated from T-cells is expressed predominantly on T-cells and cells of mesenchymal origin. It binds both types of IL1 with equal affinity. This type is called also Type 1 receptor. It has been designated CD121a. The Type 2 receptor has been designated CD121b. It is isolated from B-cells, granulocytes, and macrophages. It is expressed predominantly on B-cells and cells of the myelomonocytic lineage and is encoded by a separate gene