<prompt> Which immunoglobulin has no known function but is present on the surface of B lymphocytes and it may function as an antigen receptor?IgAIgEIg DIgM  <response>: IgD antibody consists of two light chains and two heavy chains. Its role is not known but can be found on the surface of lymphocytes where it may act as a surface receptor. Ref : Ananthanarayana textbook of Microbiology 9th edition Pgno : 98 