The monoclonal antibody 440c reacts with Siglec-H, a cell-surface receptor molecule selectively expressed on murine natural interferon producing cells (IPC), also called mouse plasmacytoid dendritic cells (pDC). Siglec H is unique among Sialic acid-binding Ig-like lectins (Siglecs) proteins because it associates with the adaptor protein DAP12. DAP12 recognize certain viruses and CpG-DNA through TLR9, resulting in secretion of IFN-alpha, IL-12 and proinflammatory chemokines. Together these cytokines and chemokines recruite and activate NK cells and T cells as well as modulating the antigen presenting function of dendritic cells (DC). IPC themselves also function as antigen presenting cells that expand memory T cells and induce Th1 differentiation. Therefore IPC may provide a first line of host defense against viral infections by activating both innate and adaptive responses in vivo. The monoclonal antibody 440c exclusively recognizes mouse Siglec-H in all lymphoid organs under both normal and inflammatory conditions. Siglec-H is normal present in the T cell zone of lymph nodes and spleen. Incubation of IPC with antibody 440c in vitro or administration of antibody 440c in vivo reduces secretion of IFN-alpha in response to CpG DNA without causing IPC depletion.
Flow cytometry, Frozen sections, Functional studies, Paraffin sections
For immunohistology and flow cytometry dilutions to be used depend on detection system applied. It is recommended that users test the reagent and determine their own optimal dilutions. The typical starting working dilution is 1:50. For inhibition of IFN-alpha secretion dilutions have to be made according to the amounts of Siglec-H to be inactivated.