The immune system has long been recognized for its importance in eliminating pathogens. Recently, it has become appreciated for additional distinct roles in normal tissue biology, contributing to tissue development and maintenance. Further, it is being revealed as a major force in diseases as diverse as fibrosis, type 2 diabetes, and Alzheimer’s disease, as well as cancer. The immune system is exquisitely selective; more than a billion different adaptive immune lymphocytes (T cells and B cells) survey the body. These can individually be sensitized to antigens … Perhaps the best-developed exemplar for an immune response that is neither focused on destruction nor tolerance, but rather on achieving tissue homeostasis, is in wound healing and tissue repair. In early wounds, infiltration of inflammatory neutrophils and monocytes provides wound sterilization. In late wound-healing responses … read more