FIG 1.

PLY is required for IL-1α secretion from S. pneumoniae-infected macrophages. Adherent PECs were infected with the D39 and Δply strains at an MOI of 1, gentamicin was added to cultures (final concentration, 100 μg/ml) 6 h later, and culture supernatants were collected after an additional 18 h of incubation (24 h after infection). (A and B) Levels of IL-1α (A) and TNF-α (B) were measured by an ELISA. UI, uninfected. (C) Macrophages were stimulated with different concentrations of rPLY (0.01 nΜ, 0.1 nM, and 1 nM). (D) Macrophages were infected with the Δply strain and treated with different concentrations of rPLY or cholesterol-treated rPLY. The levels of IL-1α in the supernatants were determined by an ELISA. Data represent the means and the standard deviations of results from triplicate assays and are representative of data from three independent experiments. Statistical significance was determined by Student's t test. *, P < 0.05.