Foreword

• Published in: Neutrophils in Infectious Diseases Vol. 1; no. 1; p. i
• Main Author: Solbach, Werner
• Format: Book Chapter
• Language: English
• Published: 01.09.2011
• DOI: 10.2174/97816080502391110101000i

More than hundred years ago, Eli Metchnikoff was the first to discover phagocytosis by macrophages and "microphages", today known as neutrophilic granulocytes, as a critical host-defense mechanism. Their life-saving role in combating acute infections is undoubted as wittnessed by potentially lethal diseases resulting from defects in number or function of neutrophils, for example iatrogenic leukopenia or rare diseases like the leukocyte adhesion deficiency syndrome, chronic granulomatous disease or congenital neutropenia. Historically, neutrophils were widely disrespected by researchers as gormless cells that crawl, eat and disgorge prepacked enzymes and reduced molecules of oxygen. This may have been due to difficulties in experimental approaches given the short half-life of the cells in vitro and in vivo. Recent advances in technology have put the neutrophils in the centre of interest for infection biologists and immunologists. They are the first cells that are able to recognize tissue injury and the presence of genomes other than those encodes in the germline of the individual. Central to this function is to sense injury and "non-self" by pattern-recognition receptors, to send alarming signals to activate epithelial and endothelial cells, mast cells, macrophages and platelets. As key component of the inflammatory response, neutrophils are instrumental to recruitment, activation and programming of antigen-presenting cells by generating chemokines, regulatory cytokines and through direct cellular contact. In addition, they make important contributions to the activation of antigenrecognizing T- and B-lymphocytes and are thus important decision-makers and decision-shapers for the success or failure of the adaptive immune system in serving the collective good. Some microbes like Chlamydia, Anaplasma or Leishmania are able to substantially prolong the usually short halflife of neutrophils (6-8 hours in the circulation, 15 hours in the petri-dish) by slowing-down the apoptotic program. Although the molecular basis of that interaction remains to be uncovered, it is clear that this mechanism paves the microorganisms to a silent entry into hosts cells and facilitates their dissemination through the organism...