Cytokines in infectious disease: the battle between host and pathogen.

The immune system is poised like a fulcrum to respond quickly to challenge by infectious agents, but can produce excess inflammatory signals or excess suppressive signals when out of balance. During the past year, significant progress has been made in our understanding of how certain pathogens promote immune suppression and shift the balance from the host in their favor. Understanding the mechanisms that underlie excessive inflammatory responses or the suppressive effects of the micro-organism will aid in the development of new therapies.