OBJECTIVES: 1) Production and characterization of monoclonal antibodies reacting with allotypes, idiotypes and B cell surface markers. 2) Monoclonal antibody analysis of IgH polymorphisms (allotypes and idiotypes). 3) Structural analysis of secreted and cell surface IgG's. 4) FACS selection of monoclonal aatibodies producing variant lines that produce antibodies with the parental Igh variable region and IgE light chain but have switched production to a different Igh constant region. 5) Examination of the mechanisms and recognition receptor involved in isotype all allotype regulation by the hapten specific system. 6) Continued examination of B cell surface markers during development.