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Macrophages and vascular adhesion molecules in oral Kaposi's sarcoma
L A MacPhail1, N P Dekker, J A Regezi
1School of Dentistry, Dept. of Stomatology, University of California, San Francisco 94143, USA.
Abstract:
Kaposi's sarcoma (KS) is a heterogeneous tumor where spindle cells are predominant and macrophages and factor XIIIa positive dendrocytes are abundant. The origin of the macrophages and dendrocytes is unclear, although their numbers suggest a critical role in KS pathogenesis. To determine if KS macrophages are recruited from the blood stream or proliferate on-site, we examined biopsy specimens 1) for expression and distribution of vascular adhesion molecules (PECAM-1, ELAM-1, ICAM-1, VCAM-1, P-selectin, L-selectin) and the macrophage-associated adhesion-molecule ligand, VLA-4; 2) for dual expression of proliferation (Ki-67) and lineage-associated markers (KP-1, CD34, factor XIIIa, LCA); and 3) for dual expression of macrophage (KP-1) and endothelial cell (CD34) associated markers. Avidinbiotin peroxidase techniques were used. Resident vessels were found to strongly express PECAM-1, ELAM-1, ICAM-1, P-selectin, and moderately express VCAM-1 and VLA-4. Tumor spindle cells showed less intense expression of ELAM-1, ICAM-1 and P-selectin. The most frequent double-stain combination was Ki-67 + CD34+. In contrast, the combinations of Ki-67 + KP-1+, Ki-67 + XIIIa+ and Ki-67 + LCA+ were rarely seen. The enhanced expression of adhesion molecules on resident vessels and the lack of evidence of macrophage proliferation suggest that the abundant macrophages in KS are recruited from the blood stream.
Insights
In Kaposi's sarcoma (KS), abundant macrophages are likely recruited from the bloodstream, not locally proliferated. This study investigated vascular adhesion molecules and cell proliferation markers in KS tissue to understand macrophage origins.
Area of Science:
- Oncology
- Immunology
- Pathology
Background:
- Kaposi's sarcoma (KS) is characterized by spindle cells, abundant macrophages, and factor XIIIa-positive dendrocytes.
- The precise origin of these macrophages and dendrocytes in KS pathogenesis remains unclear.
- Their significant numbers suggest a critical role in the disease.
Purpose of the Study:
- To investigate whether macrophages in Kaposi's sarcoma are recruited from circulating blood or proliferate within the tumor.
- To elucidate the role of vascular adhesion molecules and cell proliferation markers in KS.
Main Methods:
- Analysis of KS biopsy specimens using avidin-biotin peroxidase techniques.
- Examined expression and distribution of vascular adhesion molecules (PECAM-1, ELAM-1, ICAM-1, VCAM-1, P-selectin, L-selectin) and VLA-4.
- Assessed dual expression of proliferation marker Ki-67 with lineage markers (KP-1, CD34, factor XIIIa, LCA) and macrophage (KP-1) with endothelial cell (CD34) markers.
Main Results:
- Resident vessels in KS tissue showed strong expression of PECAM-1, ELAM-1, ICAM-1, P-selectin, and moderate expression of VCAM-1 and VLA-4.
- Tumor spindle cells exhibited less intense expression of ELAM-1, ICAM-1, and P-selectin.
- The most common double-stain was Ki-67 + CD34+, while Ki-67 + KP-1+, Ki-67 + XIIIa+, and Ki-67 + LCA+ were rare, indicating limited macrophage proliferation.
Conclusions:
- Enhanced expression of adhesion molecules on resident vessels supports the recruitment of macrophages.
- The scarcity of proliferating macrophages (Ki-67 positive) suggests limited on-site proliferation.
- Findings indicate that abundant macrophages in Kaposi's sarcoma are primarily recruited from the bloodstream.