Transient Appearance of Circulating Interleukin-6 and Tumor Necrosis Factor in Germ-Free C3H/HeJ and C3H/HeN Mice upon Intestinal Exposure to E. Coli
The intestinal lumen harbours an enormous number of bacteria. These bacteria carry and release substances, e. g., lipopolysaccharide (LPS), which are potent activators of the immune system and inflammatory reactions. Despite this, the host does not normally show any inflammatory reaction towards the intestinal flora and the blood concentration of inflammatogenic cytokines such as interleukin (IL)-l, IL-6 and TNF are generally below detection levels. In contrast, if other mucosal surfaces, e. g., the urinary tract, are colonized with Gram negative bacteria this results in the appearance of IL-6 in the urine and infiltration with neutrophilic granulocytes in the lamina propria. In this respect it is known that mice which are repeatedly administered LPS become non-responsive in terms of cytokine production.1 Whether the same type of non-responsiveness exists in response to the inflammatogenic properties of the intestinal flora is at present unknown.
Unable to display preview. Download preview PDF.