Enhancement of cytokine production and natural killer activity by an Escherichia coli extract.

OM-89 is a bacterial extract of E. coli which is clinically used in the treatment of urinary tract infections. Since immunological mechanisms may play a role in its action, its immunological effects were evaluated in vitro on peripheral blood mononuclear cells. The results showed that OM-89 enhances natural killer activity, as well as the spontaneous production of alpha-TNF and IL2. In the presence of various mitogens, it enhanced the production of IL1, gamma-IF, alpha-TNF and IL2. These data indicate that OM-89 acts on cell-mediated mechanisms by a direct and/or an indirect effect on monocytes, T cells and natural killer cells. These data suggest that the clinical activity by OM-89 may be related to its immunological properties.