For interaction assays, bacterial

cells were obtained by streaking strain ATCC 49619 on 5% sheep blood agar plates (Plast Labor, Rio de Janeiro, RJ, Brazil). After incubation at 37°C for 20 h under 5% CO2 atmosphere, individual colonies were selected and cells were suspended in Hanks’ balanced salt solution (HBSS; Sigma) to reach a turbidity equivalent to the 0.5 McFarland standard. To reduce cell clumping, the bacterial selleck compound suspension was passed 15 times through a 27-gauge needle and then allowed to settle for 15 min. Only the top fraction of the suspension containing dispersed bacteria was used to infect SCs. This dissociation Barasertib datasheet method was used only in the case of bacterial clumping. First, we determined the number of SCs using a Neubauer Chamber. Next, the bacterial inoculum was determined

by McFarland Turbidity Standards. SC cultures were infected with suspensions of living S. pneumoniae ATCC 49619 cells in a ratio of 100:1 bacteria/SC cells for at least 3 h in serum- and antibiotic-free DMEM F-12. After this period, the cultures were rinsed with PBS to remove non-adhered bacteria, DMEM F-12 was added, and the infection was followed at 37°C for up to 24 h, with fixation of infected cells at 3, 12, and 24 h after PBS rinsing. The number of SCs associated

with S. pneumoniae was determined after 3, 12 and 24 h. For the dark-field microscopy analyses, the infected and uninfected cultures were washed in PBS and fixed. The samples on cover slips, previously fixed in 4% paraformaldehyde at room temperature, were permeabilized crotamiton with PBS-Triton 0.3% and blocked with 10% NGS [27,3]. After that, bacteria were detected by using a Pneumococcal anti-serum (OMNI States Serum Institut, Caspase activation Copenhagen, Denmark) and/or stained with 0.1 mg/ml 4’,6-diamidino-phenylindole (DAPI, Sigma). The viability of the bacteria was examined using fluorescent microscopy after staining with 5 mM SYTOX Green nucleic acid stain (Invitrogen) [28]. Competition assays were performed by infecting cultures in the presence of 100 μg/ml of mannan (hyper-mannosylated glycoprotein from Saccharomyces cerevisiae – Sigma) after testing concentrations in the range of 10 to 1000 μg/ml (10, 100, 500, and 1000 μg/ml) [29,30,3] for 3 to 24 h. A cytochemical assay with (Man/BSA-FITC) binding was performed in order to determine the presence of a MR with the active CTLDs. Other infected cultures were incubated with 50 μg/ml man/BSA-FITC as described above.