IgM and IgD are the main immunoglobulins expressed on the surface of B cells, usually about 10% of serum immunoglobulins. The early immune response to most antigens is primarily IgM antibodies, which play a leading role in some antibody reactions, such as "natural" blood group antibodies. Monoclonal 8H6 was developed to reduce background staining of polyclonal antibodies in paraffin sections.