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The macrophagic origin of multinucleated giant cells in myeloma kidney: an immunohistologic study
Abstract:
The cast-engulfing giant cells in a case of kappa light chain nephropathy/Bence Jones cast nephropathy were characterized with monoclonal antibodies Uro-5 (renal epithelium: Henle's loop, distal tubule, collecting duct) and Leu-M5 (macrophage/monocyte/dendritic cell specific). The giant cells were Leu-M5 positive and Uro-5 negative. There was an increased concentration of Leu-M5-positive cells surrounding cast-containing tubules, and occasional Leu-M5-positive cells were found within the tubular epithelial layer. Although there were no Uro-5-positive giant cells, an occasional Uro-5-positive cell was found within casts. The majority of casts were found within Uro-5-positive tubules. These results confirm earlier electron microscopic reports that the cell of origin of the cast-engulfing multinucleated giant cell is the macrophage (Leu-M5 positive, Uro-5 negative). These giant cells may originate from macrophages that have migrated from the interstitium through the tubular epithelium.
Insights
Giant cells in kappa light chain nephropathy are macrophages, not renal cells. These macrophage-derived giant cells engulf Bence Jones protein casts in kidney tubules.
Area of Science:
- Nephrology
- Immunohistochemistry
- Renal Pathology
Background:
- Kappa light chain nephropathy is characterized by Bence Jones protein casts.
- Multinucleated giant cells are observed in some cases of nephropathy.
- The cellular origin of these giant cells has been debated.
Observation:
- Giant cells engulfing casts were analyzed using Uro-5 and Leu-M5 antibodies.
- Giant cells were positive for Leu-M5 (macrophage marker) and negative for Uro-5 (renal tubule marker).
- Increased Leu-M5-positive cells were found around and within tubules containing casts.
Findings:
- The cast-engulfing giant cells are of macrophage origin.
- Macrophages may infiltrate the tubular epithelium from the interstitium.
- Renal tubular cells (Uro-5 positive) were not the source of the giant cells.
Implications:
- This confirms macrophages as the source of giant cells in Bence Jones cast nephropathy.
- Understanding giant cell origin aids in diagnosing and understanding kidney disease pathogenesis.
- Macrophage migration into tubules is a key feature of this nephropathy.