Gamma heavy chain disease. Ultrastructural and immunohistochemical study.

Electron microscopic and immunohistochemical studies were carried out on materials obtained from three patients of gamma heavy chain disease (gamma-HCD). Electron microscopically, proliferating cells showed various stages of maturation from immunoblast to plasma cell, and the majority of proliferating cells were proplasmacytes and plasma cells. From the intracytoplasmic immunoglobulin studies by immunoperoxidase method (PAP method) and electron microscopical enzyme-labeled antibody technique, proliferating cells, such as the immunoblast, plasmablast, proplasmacyte, and plasma cell, showed positive reaction to anti-gamma-heavy chain serum and anti-Fc fragment (IgG) serum, and also in a third case with Bence Jones protein, proliferating cells showed positive reaction to anti-kappa light chain serum. We would conclude that proliferating cells in gamma-HCD might be a single clone proliferation of B-cell synthesizing gamma-HCD protein, and the predominant proliferation cells are proplasmacytes and plasma cells situated near mature plasma cells in the B-cell line.