Cellular and molecular aspects of inflammation.

Cellular host reaction to noxious agents and damaging events consists of inflammatory, immune and repair responses. These are usually involved in different phases of the host reaction in a well co-ordinated manner, contributing to the well-being of the host. However, when they are excessive, uncontrolled or occur in a vulnerable anatomic location, they can contribute greatly to injury. In general, the effects of the initiating stimulus are much enhanced by secondary involvement of amplification loops, leading to recruitment of nonspecific cells. The number of initially stimulated and/or actively involved cell is, therefore, usually low but of crucial importance for the outcome of the process. As important as understanding of the mechanisms responsible for initiation and amplification of the host response is knowledge of the negative feedback loops responsible for down-regulation of the whole process.