Role of C‐type lectins and activation receptors in the transmission of HIV‐1 from B cells to CD4+ T cells

Objective: Based on our previous findings that DC‐SIGN‐expressing B cells could transmit HIV‐1 to T cells (PLoS Pathog. 2:e70, 2006), we determined the relative role of other B cell surface markers in this process. Methods: B cells were activated with T‐dependent and T‐independent ligands CD40L, BAFF, CpG DNA, PHA, and LPS, and monitored for expression of C type lectins and activation markers by flow cytometry. Mabs specific for lectins or cell surface receptors were used to block transmission of HIV‐1 to T cells. Results: B cells stimulated with CD40L, BAFF or LPS had enhanced expression of C type lectins and activation receptors, and transmitted HIV‐1 to T cells. In contrast, B cells stimulated with CpG DNA and PHA were activated but did not transmit HIV‐1 to T cells. Blocking DC‐SIGN with mAb prior to loading with HIV‐1 inhibited virus transmission to T cells. Conclusions: B cells can be activated by both T‐dependent and T‐independent ligands to express C type lectins. This activation state determines their ability to transmit HIV‐1 to T cells, extending our previous results that DC‐SIGN is needed for B cell mediated transmission of HIV‐1 to T cells. (AI35041, CA82053, AI41870)