Fig. 2.

Platelet activation by Candida yeast cells. a Platelets (plts) were stained with an FITC-labelled α-CD41 antibody, followed by the incubation for 90 min with medium, thrombin, or a 5-fold excess of calcofluor-stained yeast cells of C. albicans (CA1, CA3), C. glabrata (CG1), C. auris (CAU1), C. krusei (CK1), C. lusitaniae (CL1), C. parapsilosis (CP1), C. rugosa (CR1) or C. tropicalis (CT1). C. albicans isolates SC5314 and SN152 were used as reference strains. Exposure of the platelet activation marker CD62P was assessed by flow cytometry and expressed as mean fluorescence intensity (mean). b Platelet activation was confirmed by confocal microscopy using PE-labelled α-CD62P antibody for activated platelets (red); platelet presence is shown in upper image (green), activity in the middle, and overlay in bottom image. c Whole blood was incubated in RPMI medium alone or additionally with ADP as a positive control, or calcofluor-labelled C. albicans (CA1) yeast cells (fivefold excess over platelet number), respectively, for 90 min. Activity was evaluated by flow cytometry analysis of CD62P. For both PRP and whole blood, activation of all platelets (CD41+ events) was compared with the subpopulation of Candida-bound platelets (calcofluor+ and CD41+ events). All experiments were performed in triplicates and repeated at least 3 times with different platelet donors; representative results are shown here. Activity of samples with Candida were compared to medium control by one-way analysis of variance; * p < 0.05; ** p < 0.01; *** p < 0.005; **** p < 0.001.