Plural immunoglobulin synthesis in a single cell: An ultrastructural studyof two cases with three M-proteins

Electrophoresis revealed two cases of malignant lymphoma that each containe d three M-proteins (IgM lambda.IgG kappa.IgG lambda and IgM lambda.IgM kapp a.IgG kappa) in the sera. To determine cellular origin of each M-protein, a typical lymphoid and plasmacytoid cells of both cases were examined by elec tron microscopy. Atypical lymphoid and plasmacytoid cells possessed rough e ndoplasmic reticula (RERs) in varying degrees, as seen by conventional elec tron microscopy, and showed double-stainability for plural antibodies again st immunoglobulins following double stainings of immunoelectron microscopy using immunogold staining. Rabbit antibodies against human IgM, IgG, free k appa-light chain and free A-light chain were used for the immunoelectron mi croscopic staining. By the double staining method, plural immunoglobulins, IgM/IgG, IgM/free kappa, IgM/free lambda, IgG/free kappa, IgG/free lambda a nd free kappa/free lambda, were simultaneously detected in varying degrees in the Golgi area, RERs, and dense bodies of lymphoid and plasmacytoid cell s. In conclusion, this study directly exhibited, through electron microscopy, that plural immunoglobulins were synthesized at the same time in a single c ell, and that the process of immunoglobulin synthesis in the lymphoid and p lasmacytoid cells was different from that in a normal B-cell.