Discordances of cytoplasmic immunoglobulin G staining with the immunoperoxidase technic in plasma cells from bone marrow, tonsils, and appendix

Plasma cell cytoplasmic immunoglobulin was stained using the peroxidase-antiperoxidase technic in Bouin-fixed, paraffin-embedded human tissues from different origins. Bone marrow (BM), tonsils, and appendices were examined. IgA-, IgD-, and IgM-secreting plasmocytes were easily studied using highly diluted rabbit antihuman antisera in all tissues, including BM. IgG plasmocytes showed good stainability in tonsils and appendices, but variable results were obtained in BM. Bone marrow IgG plasmocytes from persons without infection required a tenfold higher concentration of rabbit antihuman IgG than plasmocytes derived from patients with infection. Stainability of BM plasmocytes from patients with infection was equal to BM plasmocytes from myeloma patients. Because the same rabbit antihuman IgG concentration could be applied for staining plasmocytes derived from tonsils and appendices, it is most probable that the difference in staining ability is due to a difference in activity of the plasmocytes, i.e., a different IgG concentration in the plasmocytes.