In order to better understand the relationship between IL-1β expression and infection by P. gingivalis and S. mitis, we conducted a dose-dependent (MOI = 0.5, 5, and 50) time course (2, 6, and 24 h) to measure expression of IL-1β in human THP-1 cells in response to exposure to P. gingivalis and S. mitis using qRT-PCR, western blot, and ELISA analysis. This evidence concerns the gene IL1B and infection.