Matrix metalloproteinases (MMP) are zinc- or calcium-dependent proteinases involved in the normal maintenance of the extracellular matrix. When elevated, MMPs degrade matrix components contributing to tissue destruction in infected periodontal sites. The objectives of this study were two-fold: first to assess the ability of Porphyromonas gingivalis hemagglutinin B (HagB) to induce MMP responses in human myeloid dendritic cells and second, to assess the effect of host defense peptide human ß defensin 3 (HBD3) to regulate and attenuate the MMP response of HagB treated dendritic cells. HBD3 (0.2, 2.0, or 20.0 µM) was given to primary dendritic cells pre-, co-, or posttreatment to HagB (0.02 or 0.2 µM). At 16 hours, MMP concentrations were determined. There were no significant differences in concentrations for all 3 replications for MMP-2 and -13. There were few significant differences in some of the replications for MMP-3, -7, and -9. There were more pronounced differences in MMP-1, -10, and -12 expression, which were significantly influenced by both the concentration of HBD3 and the timing of administration. Chemokine and cytokine responses were inversely related to MMP production. While MMP responses decreased in a dose related manner, chemokine responses were increased. Concentrations of MIP-1a were high and there were no differences in response to 0.02 and 0.2 M HagB with or without 20.0 ?M HBD3. However, the MIP-1ß and TNFa response to 0.2 ?M HagB were only attenuated. HagB induces the production of MMPs in dendritic cells and treatment of dendritic cells with HBD3 can alter the profile of HagB-induced MMPs. Such a finding may have importance in the pathogenesis of periodontal disease.