Host Reactive Cell

A host reactive cell refers to an immune cell, most often a T lymphocyte, that recognizes and reacts against antigens presented by the host organism. This reactivity is particularly significant in contexts such as transplantation (e.g., graft-versus-host disease, GVHD) or chimeric states where immune cells from one individual encounter the tissues of another. These cells can mediate tissue injury by targeting host tissues expressing non-self major histocompatibility complex (MHC) molecules or minor histocompatibility antigens. Host-reactive T cells are central mediators of GVHD following allogeneic hematopoietic stem cell transplantation. They recognize alloantigens on host tissues and initiate inflammatory responses leading to tissue damage.