Recent developments in IBD and the B7 family of costimulatory molecules

The cells and tissues of the intestinal tract are subjected to a constant onslaught of antigenic challenge from both beneficial and harmful pathogens. Despite this constant stimulation, the host is able to maintain a relatively stable environment, often referred to as 'a controlled state of inflammation'. In patients with chronic inflammatory bowel disease, this controlled state of inflammation is lost. The cause of this loss of control is not fully understood, but there is emerging research interest in positive and negative costimulatory pathways as potential targets for modulating the dysregulation. This review describes the B7 and B7-like butyrophilin families of costimulatory molecules, with an emphasis on the role of costimulation in intestinal inflammation.