Patients With Bone Marrow Failure Demonstrate Decreased Cutaneous Reactivity to Human C5a

Abstract In vivo studies have shown that human C5a, a potent complement-derived anaphylatoxin and chemoattractant, produces immediate inflammatory reactions following intradermal injection in human skin. At concentrations within its potential physiologic range, intradermal injection of C5a elicits immediate wheal and flare reactions, increased vascular permeability, mast cell degranulation, and neutrophil-rich infiltrates. To assess the relative contribution of interacting cellular elements to C5a-induced inflammation in normal human skin, purified human C5a was tested intradermally in 8 patients with bone marrow failure (BMF). Reactions to C5a in patients with BMF were compared with responses at identical test sites in healthy volunteers and other patients with cutaneous disorders. Patients with BMF demonstrated significantly less wheal and flare reactivity following intradermal injection of C5a than controls ( p