Description: The 33D1 monoclonal antibody reacts with a mouse DC-specific surface marker. The nature and biological activity of the 33D1 antigen is as of yet unknown. 33D1 has been reported on a variety of dendritic cell subpopulations from mouse thymus, spleen, lymph node, and Peyer’s patch. Bone marrow dendritic cells require GM-CSF to express the 33D1 antigen and this expression is down regulated in the presence of IL-4. 33D1 antigen has been detected in vivo in brain dendritic cells post infection via Toxoplasma gondii.