Inflammation is a vital process by which the body is able to fight infection and heal wounded tissue. However inappropriate control of inflammation is responsible for a wide range of pathologies (e.g. rheumatoid arthritis, inflammatory bowel disease). One of the hallmark features of inflammation, and one of the key pathogenic mechanisms in inflammatory disorders is leukocyte recruitment. Therefore understanding the molecular mechanisms by which leukocytes travel from the bloodstream to the extravascular tissue is of great importance.

Evidence suggests that there is a cascade of complex interactions between leukocytes and endothelium that to be fully understood must be studied on-line rather than using endpoint readouts such as tissue levels of leukocyte enzymes (myeloperoxidase) or histological techniques. A number of laboratories, including our own, have used a technique known as intravital microscopy to directly visualize leukocyte trafficking in individual vessels in a range of tissues, in an attempt to gain a better understanding of the mechanisms of leukocyte recruitment. Intravital microscopy entails microscopic examination of living tissues.