Ferritin H Is a Novel Marker of Tumor-Associated Macrophages and Its Expression Is Associated with Tumor Grade
Wei Wang, Frank M Torti, Suzy V Torti, Michael W Beaty. Wake Forest Baptist Health, Winston Salem, NC; University of Connecticut Health Center, Farmington, CT
Background: Macrophages are a main component of tumor microenvironments and play a critical role in tumor survival, growth and metastasis. In follicular lymphoma, the number of lymphoma-associated macrophages is an independent prognostic factor. Increased numbers of macrophages in neoplastic follicles correlates with a poor prognosis. In Hodgkin's lymphoma, an increased number of macrophages is associated with a shortened progression-free survival and an increased likelihood of relapse. CD68 is currently the most commonly used marker of tumor associated macrophages. CD68, however, is not a macrophage-specific antigen and is generally considered an organelle- rather than cell lineage-specific marker, recognizing glycoproteins present in lysosomes, phagosomes, and neutrophil primary granules. We recently developed a novel lineage-specific macrophage antibody, ferritin H. In this current study we aimed to investigate whether ferritin H is a marker of tumor associated macrophages and whether its expression is associated with tumor grade.
Design: Ferritin H immunohistochemistry was performed using a monoclonal antibody generated by hybridoma. Cases used in this study included normal lymph nodes (19), chronic lymphocytic leukemia/small lymphocytic lymphoma (8), follicular lymphoma (12), mantle cell lymphoma (5), and diffuse large B cell lymphoma (11).
Results: In normal lymph nodes, ferritin H is positive in macrophages, while negative in all other cells, including normal T and B cells. In lymphomas, ferritin H specifically stains and highlights tumor associated macrophages while neoplastic lymphoid cells are completely negative. The number of tumor associated macrophages in low grade lymphoma (CLL/SLL, mantle) is substantially less than the number in high grade lymphoma (DLBCL). Within follicular lymphoma (Figure 1), grade 1/2 lymphomas (A,H&E; B,Ferritin H) show fewer tumor-associated macrophages than grade 3 lesions [C,H&E; D,Ferritin H).
Conclusions: Ferritin H is a novel and reliable marker of tumor associated macrophage in various lymphomas. Its expression level is associated with tumor grade.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 239, Monday Morning