title: Ki-M6 immunostaining in routinely processed sections of reactive and neoplastic human lymphoid tissue.
abstract: A monoclonal antibody, termed Ki-M6 (CD68), which shows a restricted reactivity to cells of the monocyte/macrophage system, has been evaluated primarily with the use of cryostat sections. In this study the authors could assess that the Ki-M6 antibody recognizes a fixation-resistant epitope in most human macrophages. The Ki-M6 immunoreactivity with monocyte/macrophage-related cells was established by testing on routinely processed samples of reactive and neoplastic lymphoid tissues; it was compared with the staining for vimentin (V9) and S-100 protein antibodies, with visualization of the stationary elements of lymphoid tissues, with the aim of establishing its value in the study of the nonlymphoid microenvironment. The Ki-M6 antibody reactivity could be achieved with Bouin-fixed, paraffin-embedded tissue sections, without any proteolytic treatment, with the use of the avidin-biotin complex (ABC) method, especially after overnight incubation time at 4 degrees C. Some reduction in antigenic reactivity was observed in B5- or formaldehyde-fixed samples. The antibody reacted with macrophages of all different lymph node compartments; a broad reactivity against cells of macrophage lineage, including multinucleated giant cells, was observed in epithelioid granulomas. Ki-M6-positive cells other than classic macrophages were the so-called "plasmacytoid T-cells" and cells displaying elongated cytoplasms with fibroblastic-like features. Granulocytes, follicular dendritic reticulum cells, and interdigitating reticulum cells did not reveal any reactivity with Ki-M6 antibody. In malignant lesions, neoplastic cells of follicular and diffuse B- and T-cell lymphomas, including large cell non-Hodgkin's lymphomas, and Reed-Sternberg cells of Hodgkin's disease were negative in all cases studied. This study shows that Ki-M6 seems to be another anti-macrophage-specific antibody that reacts, in routinely processed tissue sections, with tissue macrophages but not with accessory cells. Thus, it may be a valuable addition to vimentin and S-100 protein antibodies for investigation of the microenvironmental organization of lymphoid tissues both in normal and neoplastic conditions.
authors: Division of Pathology, Centro di Riferimento Oncologico, Aviano, Italy.
authors: A
authors: A
authors: Gloghini
authors: R
authors: R
authors: Volpe
authors: A
authors: A
authors: Carbone
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D006689:Hodgkin Disease / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008221:Lymphoid Tissue / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008228:Lymphoma, Non-Hodgkin / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D009000:Monocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D009418:S100 Proteins / Q000276:immunology / Q000378:metabolism; D014746:Vimentin / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D009418:S100 Proteins; D014746:Vimentin