Ligation of dendritic cell-associated lectin-1 induces partial maturation of human monocyte derived dendritic cells.

Dendritic cell-associated lectin-1 (DCAL-1), also known as C-type lectin-like-1 (CLECL1), is a novel C-type lectin-like molecule expressed by antigen presenting cells including dendritic cells (DCs). Here we report that incubation of immature DCs (iDCs) with an anti-DCAL-1 monoclonal antibody (mAb) induced downstream signaling, including phosphorylation of c-Jun N-terminal kinase (JNK) and p44/42 MAP kinase. Furthermore, ligation of DCAL-1 expressed by iDCs specifically enhanced HLA-DR expression, whereas the expression of other co-stimulatory molecules remained unchanged and minimal cytokine secretion was detected. DCs that express high levels of major histocompatibility complex (MHC) class II in the absence of high levels of other co-stimulatory molecules and inflammatory cytokine secretion may play an important role in the maintenance of immune tolerance. Therefore, our data suggests an important role for DCAL-1 in the regulation of the immune response.