Topographical localization of intracellular immunoglobulins in hairy cells by immunoelectron microscopy.

Ultrastructural characterization and localization of intracellular immunoglobulin in peripheral blood mononuclear cells from a patient with hairy cell leukemia were studied by the direct immunoperoxidase technique. Approximately 20--30% of hairy cells stained positive for gamma-heavy and K-light chains, and this staining was limited to certain rough endoplasmic reticulum profiles. These ultrastructural findings can be considered an additional argument for the B cell origin of hairy cells.