The membrane-bound mucin MUC1 is expressed ubiquitously on epithelial surfaces and is thought to provide protection from bacterial and chemical injury. The present study was undertaken to determine whether MUC1 was expressed in cultured oral epithelial cells and whether expression is modulated by pro-inflammatory mediators released as part of the host response to infection by oral pathogens. Northern and Western blotting experiments showed that KB cells express MUC1 mRNA and protein. When cells were treated with interleukins (IL-1beta, IL-6), tumor necrosis factor-alpha (TNF-alpha), or interferon-gamma (IFN-gamma), or combinations of these, real-time PCR demonstrated that MUC1 mRNA increased 1.4- to 3.2-fold. Interestingly, a significant increase in levels of MUC1 protein was also observed. While no effect was observed when KB cells were incubated with LPS from Porphyromonas gingivalis, infection of KB monolayers with this oral pathogen caused a 2.85-fold increase in MUC1 transcript levels. These results suggest that increased MUC1 synthesis may be a key element in the host response to infection with oral pathogens.