[Immune mechanisms implicated in vasculitis]

Vasculites are inflammatory reactions of the blood vessels. Diverse and intense clinical manifestations depend mostly on the magnitude of the associated immune response, the size of the vessels and the organs that they supply. The hypersensitivity reactions implicated in their pathogeny are mainly of type III; they involve immune complexes, complement activation and tissue infiltration with neutrophile polynuclear cells, as in Arthus' phenomenon.