Confocal microscopy images showing expression of the mannose receptor (MR) in uninfected and infected Schwann cells (SCs) by Streptococcus pneumoniae . (A) Optical sections showing the expression of S100-β in infected Schwann cells (SCs) cultured from the adult sciatic nerve. (B and C) Double immunolabeled images, showing in B, uninfected SCs labeled for S100-β in red (maximum nuclear diameter), and in C, the same cells immunolabeled for the mannose receptor (cMR) conjugated with Alexa Fluor 488. The same field demonstrates that all S100-β+ cells are also labeled with cMR (plane at or near the free surface of the membrane). (D) Optical section, where SCs infected by S. pneumoniae for 3 h were immunolabeled for cMR (red). Bacteria were stained with DAPI (blue). Orthogonal z-sections in the horizontal and vertical planes reveal S. pneumoniae adhered (arrow) or internalized (arrowheads) by SCs (D). The nuclei were counterstained with DAPI. These results are representative of five separate experiments. Scale bar = 18 μm in (A); 18 μm in (B - C); 12 μm in (D).