C5a as a mediator of cutaneous inflammation

C5a is an 11,000-dalton fragment of the fifth component of complement with potent anaphylatoxic and leukocyte chemotactic activities. Because C5a may play an important role in selected skin disorders as well as in systemic diseases with cutaneous manifestations, we have studied the clinical and histologic alterations produced by the intradermal injection of this potent soluble mediator of inflammatin in human skin in vivo. These studies have outlined the biologic properties of human C5a within the context of cells resident in the skin, the cutaneous microvasculature, and interacting cellular elements of peripheral blood.