title: Spontaneous enzymatic cleavage of IgD myeloma protein giving a pattern of delta heavy chain disease.
abstract: The monoclonality of myeloma proteins is usually demonstrated by their electrophoretic homogeneity and their reactivity with monovalent antisera directed against isotypic determinants of a single heavy chain and a single type of light chain. The absence of precipitation with anti-sera to immunoglobulin kappa and Lambda light chains is a constant character of heavy Chain Disease Proteins (HCDP). However, homogeneous M-components present in the sera of some patients and reacting only with anti-heavy-chain antisera were identified as IgA and IgD myeloma proteins bearing unreactive Lambda chains. In this study, the electrophoretic pattern of a patient serum showed a paraprotein with heterogeneous electrophoretic mobility and precipitation reaction limited to anti-IgD antiserum. The failure to react with anti-light chain antisera was observed by immuno-electrophoresis, immunofixation and rocket-immunoselection. Further analysis by crossed-immunoelectrophoresis revealed that IgD paraprotein contained two separate populations of molecules, one of them being retained when anti-Kappa and Lambda light chains anti-bodies were incorporated in the first dimension gel. It soon became obvious that the observed pattern was generated by enzymatic cleavage of native IgD myeloma protein.
authors.forename: H
authors.initials: H
authors.lastname: Rabhi
authors.forename: M
authors.initials: M
authors.lastname: Ghaffor
authors.forename: M C
authors.initials: MC
authors.lastname: Abbadi
mesh_terms: D003937:Diagnosis, Differential; D010450:Endopeptidases / Q000378:metabolism; D006362:Heavy Chain Disease / Q000097:blood*; D006801:Humans; D007106:Immune Sera; D007122:Immunoelectrophoresis / Q000379:methods; D007072:Immunoglobulin D / Q000276:immunology / Q000378:metabolism*; D007140:Immunoglobulin Fab Fragments / Q000032:analysis; D007141:Immunoglobulin Fc Fragments / Q000032:analysis; D007147:Immunoglobulin Light Chains / Q000276:immunology / Q000378:metabolism*; D007138:Immunoglobulin delta-Chains / Q000276:immunology; D009194:Myeloma Proteins / Q000276:immunology / Q000378:metabolism*; D011233:Precipitin Tests
chemical_list: D007106:Immune Sera; D007072:Immunoglobulin D; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007147:Immunoglobulin Light Chains; D007138:Immunoglobulin delta-Chains; D009194:Myeloma Proteins; D010450:Endopeptidases