Immunoglobulin

The term is sometimes interchangeably used with antibody, a protein that is produced by B cells (in terminally differentiated B-cells known as plasma cells these immunoglobulins are produced and secreted and are not cell surface bound) which recognize and bind to other proteins or substances (foreign or self antigens). Antibodies can be part of an immune response and help eradicate viruses and bacteria or may be part of an autoimmune destructive processes in hematology such as autoimmune hemolytic anemia or immune mediated platelet destruction (e.g. ITP). The different classes of antibodies are usually based on their heavy chains (e.g. IgA, IgG, IgE, IgD, & IgM).