Patients with abnormal regulation of inflammation and with host defense defects often have an exaggerated or depressed inflammatory response with resultant difficulty in healing of recurrent infections. Delayed healing can be manifested by either a delay in wound healing, granuloma formation along the incision line, or dehiscence of a partially healed wound without evidence of infection. We are interested in studying the dynamics of host immune defenses during an experimentally induced inflammatory response using a well-studied suction blister device. This protocol is designed to study mediators of inflammation in patients with host defense defects as well as patients with excessive inflammation as in the vasculitis syndromes. We will measure mediators of inflammation (e.g., C5a, leukotriene B4, interleukins, chemokines, tumor necrosis factor, interferon-gamma) by ELISA, radioimmunoassay, High Performance Liquid Chromatography, multiplex cytokine assays, and/or bioactivity assays. Furthermore, molecular characterization and host defense functions (e.g., respiratory burst, chemotaxis, phagocytosis, microbicidal activity) of cells recruited to the blisters will also be examined. In addition to the analysis of cell function, RNA will be prepared and subject to DNA microarray or quantitative RT-PCR studies to measure expression and dynamics of key inflammatory mediators. Many of these factors contribute to the inflammatory process and several are thought to be important in granuloma formation. If patients are found to have abnormal amounts of these mediators when compared to normal volunteers or patients with other abnormalities it will help us understand the basis for their disease and new therapeutic strategies. For example, this blister study allowed us to identify a patient subsequently shown to have IRAK4 deficiency.