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Immunocytochemical characterization of a monoclonal antibody directed against mitochondria reactive in
L M Weiss1, M J Gaffey, M J Warhol
1Department of Pathology, City of Hope National Medical Center, Duarte, California.
Abstract:
The monoclonal antibody mES 13 was previously produced against bacterially expressed BALB ras p21 and was reported to have both membrane and cytoplasmic reactivity in formalin-fixed, paraffin-embedded tissue sections. In the current study, the cytoplasmic reactivity of mES 13 is investigated and demonstrated to be mitochondrial. Immunoelectron microscopic studies showed specific labeling of mitochondria without labeling of other organelles. In normal tissues, the antibody strongly labeled tissues known to have large amounts of mitochondria such as renal tubules, hepatocytes, and myocardium. The pattern of reactivity of tumors generally mimicked that of normal tissues, with carcinomas and melanomas usually showing stronger staining than sarcomas and lymphomas. Two granular cell tumors were negative. Among renal neoplasms, mES 13 strongly labeled renal oncocytomas and granular cell renal cell carcinomas and showed weaker staining of clear cell and chromophobe cell tumors. The mES 13 antibody should be useful in the characterization and diagnosis of tumors in which oncocytoma is in the differential diagnosis, especially when only paraffin-embedded tissue is available for study.
Insights
The monoclonal antibody mES 13 specifically targets mitochondria, not just general cytoplasm. This finding aids in diagnosing tumors like oncocytomas using paraffin-embedded tissues.
Area of Science:
- Immunohistochemistry
- Mitochondrial research
- Cancer diagnostics
Background:
- The mES 13 monoclonal antibody was initially characterized for reactivity against BALB ras p21.
- Previous studies reported both membrane and cytoplasmic reactivity in formalin-fixed, paraffin-embedded tissues.
Purpose of the Study:
- To investigate and confirm the specific cellular localization of the mES 13 antibody's cytoplasmic reactivity.
- To evaluate the utility of mES 13 in tumor characterization and diagnosis.
Main Methods:
- Immunoelectron microscopy was employed to precisely identify the target of mES 13.
- Antibody reactivity was assessed across various normal tissues and tumor types, including renal neoplasms.
Main Results:
- mES 13 specifically labels mitochondria, excluding other organelles.
- Strong staining was observed in normal tissues rich in mitochondria (renal tubules, hepatocytes, myocardium).
- Tumor staining patterns generally mirrored normal tissue distribution, with variations among tumor types (carcinomas, melanomas, sarcomas, lymphomas).
Conclusions:
- The mES 13 antibody demonstrates specific mitochondrial reactivity.
- Its utility is highlighted in diagnosing tumors where oncocytoma is a differential diagnosis, particularly with paraffin-embedded samples.