Immunoglobulin M, or IgM for short, is a basic antibody that is present on B cells. It is the primary antibody against A and B antigens – HERPES

Immunoglobulin M, or IgM for short, is a basic antibody that is present on B cells. It is the primary antibody against A and B antigens on red blood cells. IgM is by far the physically largest antibody in the human circulatory system.