Splenic pulp, plasma cells and foamy histiocytes in immune thrombocytopenia: Combined morphometric immunohistochemical and ultrastructural studies

Abstract

Spleens from 16 splenectomized patients with immune thrombocytopenia (ITP) were compared with 10 controls (accidental and incidental splenectomy, staging laparotomy). Fresh unfixed material was secured for smears and cryostat sections and splenic tissue was fixed by perfusion for histomorphometric, immunohistochemical and ultrastructural examination. The volumes of white pulp, including germinal centers, red pulp and trabecula and vessels were estimated. The ratio plasma cells containing various Ig-classes/total nucleated cells and the ratio immature/mature plasma cells were determined and the occurrence and character of foamy cells examined. There were slightly increased absolute volumes of white pulp, red pulp and trabecula + major vessels in ITP, but the differnece were not statistically significant. There was a statistically significant raised number of IgG-containing, IgA-containing and IgM-containing plasma cells in the germinal centers in ITP. More IgG-containing cells seemed to be immature than in controls, but the difference was not statistically significant. Light microscopy showed foamy histiocytes in 7 of 16 cases, but electron microscopy showed them in all cases of ITP. Foamy histiocytes reacted with antithrombocyte serum.