Fig. 7

a-d. CRAMP-deficiency resulted in decreased microglial phagocytosis rate of Streptococcus pneumoniae. Microglial cells from CRAMP-KO or wild-type (WT) mice were exposed to S. pneumoniae (strain R6) for 30 and 90 min. The intracellular bacteria were enumerated by quantitative plating of the lysates on sheep blood agar plates (a). To evaluate intracellular survival of bacteria inside microglial cells, microglial cells from CRAMP-KO or WT were exposed to S. pneumoniae (strain R6) for 30 min and bacteria quantitatively dertermined at various time points (for details refer to Material & Methods) (b). (c) Microglial cells from CRAMP-KO or WT were exposed to S. pneumoniae (strain R6) for 30 min and 1 h. The intracellular bacteria were labelled by immunofluorescence with a rabbit anti-pneumococcal antibody and detected by anti-rabbit anti-Cy3 secondary antibody (in red; cell nucleus in blue). (d) Intracellular bacteria were quantified und analysed. These results were calculated for at least 20 separate cells. The experiments were performed independently at least three times. Statistical significance is marked as * - p < 0.05, ** - p < 0.01 or *** - p < 0.0001 (Student’s -test)