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Parallel intraylysosomal amyloid fibrils, a possible result of phagocytosis
Abstract:
Vacuoles of mesenchymal cells in the papillae of bovine kidneys with amyloidosis were studied by histochemical electron microscopy for acid phosphatase as a marker for lysosomes. The vacuoles contained parallel amyloid fibrils. The vacuoles of reticular interstitial cells were found to be lysosomes. Vacuoles of macrophage-like cells of the same papillae were positive, partially positive, or negative for the enzyme activity. A suspension of papillary material was injected subcutaneously in rats in a 21-day light and electron microscopy and enzyme histochemistry study. Amyloid was demonstrated in vacuoles of macrophages throughout this period and initially also in neutrophils. In most vacuoles amyloid fibrils were randomly arranged but in others parallel arrangement was demonstrated. Amyloid was only at the inoculation sites. Intralysosomal bovine amyloid may occur in parallel fibrillar arrangement without a definite indication for amyloid production.
Insights
Bovine amyloid fibrils were found within lysosomes of kidney cells and macrophages in rats. This suggests intralysosomal amyloid may not indicate active amyloid production.
Area of Science:
- Veterinary pathology
- Cell biology
- Biochemistry
Background:
- Amyloidosis is a condition characterized by the abnormal deposition of amyloid proteins.
- The cellular mechanisms and origins of amyloid deposition are not fully understood.
- Lysosomes play a role in cellular degradation and waste removal.
Purpose of the Study:
- To investigate the presence and arrangement of amyloid fibrils within vacuoles of bovine kidney mesenchymal cells.
- To determine if these vacuoles function as lysosomes using acid phosphatase as a marker.
- To examine the fate of bovine papillary amyloid material when introduced into rats.
Main Methods:
- Histochemical electron microscopy was used to study vacuoles in bovine kidney papillae.
- Acid phosphatase staining was employed to identify lysosomes.
- Bovine papillary material was injected subcutaneously into rats for a 21-day observation period.
- Light and electron microscopy, along with enzyme histochemistry, were performed on rat tissues.
Main Results:
- Vacuoles in bovine kidney papillae contained amyloid fibrils, some with parallel arrangements.
- Vacuoles in reticular interstitial cells were identified as lysosomes.
- In rats, amyloid was found in macrophage vacuoles throughout the 21-day study and initially in neutrophils.
- Amyloid fibrils in rat vacuoles were mostly randomly arranged, but some showed parallel alignment.
- Amyloid deposition was confined to the inoculation sites in rats.
Conclusions:
- Intralysosomal bovine amyloid can exhibit a parallel fibrillar arrangement.
- The presence of amyloid within lysosomes does not necessarily indicate active amyloid production by the cell.
- Further research is needed to elucidate the precise mechanisms of amyloid formation and clearance.