Activation of human monocyte-derived dendritic cells by Burkholderia pseudomallei does not require binding to the C-type lectin DC-SIGN

Summary Dendritic cells (DCs) are essential in regulating adaptive immunity. DC-SIGN (DC-specific ICAM-grabbing nonintegrin) is a C-type lectin receptor that is expressed mainly by DCs. Accumulating evidence supports that certain pathogens target DC-SIGN to escape host immunity. To investigate a possible role of DC-SIGN in Burkholderia pseudomallei infection, we initially screened its DC-SIGN binding activity by an ELISA method utilizing a DC-SIGN-Fc chimeric protein and found that all of the B. pseudomallei strains tested failed to bind DC-SIGN. However, one strain, the LPS mutant SRM117, which lacks the type II O-polysaccharide expression, actually bound DC-SIGN, in contrast to its wild-type counterpart 1026b ( P P H 1/T H 2 differentiation. Altogether, these data suggest that, unlike other certain host pathogen interactions, activation of DCs by B. pseudomallei is not dependent on DC-SIGN. We also found evidence that the LPS mutant that binds DC-SIGN has a suppressive effect on DC cytokine production.