Binding and uptake of B3501 and B-4131 with human brain endothelial cell line, hCMEC/D3.

<p>HCMEC/D3 cells were exposed to <i>C. neoformans</i> serotype D wild type B3501 and its isogenic acapsular mutant B4131 for 2 hr and 4 hr at 37°C. Microscopic and live CFU counts were performed to determine the association and survival of cryptococci. (A) Association efficiency of B3501 and B4131 cryptococci with hCMEC/D3 cells. Like the H99-cap59 pair, live CFU counts showed a time dependent decrease in the number of associated cryptococci by 4 hr of incubation, ★ = P<0.01, ★★ = P<0.01 for both B3501 and B4131. There was no difference in association by encapsulated B3501 and acapsular B4131, P-value = >0.05 at 2 hr of incubation. However, B4131 was significantly more associated, P = 0.02 (Microscopy) and <0.01 (CFU) by 4 hr of incubation. (B) Internalization of encapsulated B3501 and its acapsular mutant derivative B4131 by hCMEC/D3 cells determined by fluorescence microscopy (Mic). The number of phagocytosed cryptococci increased significantly in a time dependent manner, P = 0.01 for both strains. However, there was no difference in internalization of B3501 and B4131, P = 0.5 and 0.2 at 2 hr and 4 hr respectively. Error bars are standard error of the mean, n = 6 repeats.