Cross-Linking of Membrane CD43 Mediates Dendritic Cell Maturation

Abstract

CD43/leukosialin is a major sialoglycoprotein of the dendritic cell (DC) surface, which can regulate cell adhesion and has the potential to mediate cell activation signals. Monocyte-derived DC transiently incubated with the anti-CD43 mAb, MEM-59, or with F(ab′)2 fragments, but not with monovalent Fab fragments or control IgG, 24 h later showed increased levels of membrane HLA-DR, CD54, CD40, CD80, CD86, and CD83. In parallel, CD43 cross-linking induced synthesis and release of IL-1β, IL-6, TNF-α, IL-12, and IL-10. CD43 ligation inhibited the endocytic activity of DC, and enhanced the capacity of DC to stimulate T cell proliferation in the primary allogeneic and autologous MLR assay. In addition, anti-CD43-treated DC were less efficient at presenting native HIV-1 reverse transcriptase to a specific CD4+ T cell clone, whereas presentation of the reverse transcriptase 55–72 peptide to the same clone was increased. Finally, MEM-59 or its F(ab′)2 fragments elicited a rise in intracellular free calcium and tyrosine phosphorylation of a 25-kDa protein in DC. The results thus indicate that CD43 cross-linking with specific ligands induces activation and functional maturation of DC.