IL6 and bacterial infectious disease: Soon after the discovery of the polyfunctional cytokine interleukin-6 (IL-6) in the early 1980s it became apparent that this cytokine was readily expressed in and secreted by a variety of cell types in response to a large number of stimuli, including viral and bacterial infections, sterile inflammation, tissue injury, and in response to other cytokines and growth factors including interleukin-1, tumor necrosis factor and platelet-derived growth factor (reviewed in [1]).