Effect of concanamycin B on CD1a-, CD1b-, and CD1c-mediated antigen presentation. Monocyte-derived dendritic cells were preincubated with 10 nM concanamycin B (con B) for 30 min and then washed and incubated for 4 h with indicated concentrations of specific M.tb antigen preparations [the semipurified M.tb lipid antigen preparation for CD8–2/J.RT3, purified glucose monomycolate (GMM) for LDN5/J.RT3, the chloroform/methanol extract of H37Ra for CD8–1/J.RT3] either in the presence or absence of 10 nM concanamycin B. The cells were then washed, fixed, and incubated with CD8–2/J.RT3 (Left), LDN5/J.RT3 (Center), and CD8–1/J.RT3 (Right), respectively, and IL-2 release into the media was measured.