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Published on: March 17, 2014
Acidophilic macrophage pneumonia in laboratory mice
1GSF-Institut für Pathologie, Neuherberg, Federal Republic of Germany.
Abstract:
Acidophilic macrophage pneumonia, characterized by an accumulation of characteristic crystalloid-laden alveolar macrophages, was seen in 30/7,500 NMRI, 7/600 T x HT, 2/100 C57BL and in no cases of 1,500 CBA and 1,100 BALB/c mice. Histologically, there was a focal accumulation of large numbers of eosinophilic macrophages, generally associated with granulocytes. Macrophages could be mononucleate or multinucleate and had a crystalline cytoplasm. Free-lying crystals were sometimes observed. Ultrastructurally, macrophages had a cytoplasmic accumulation of needle-shaped and rhomboidal crystals, often showing a clear lattice structure with a repeat of 3-5 nm. The crystalloid inclusions may be derived from the breakdown products of granulocytes and appear similar to inclusions in macrophages in other parts of the hematopoietic system. That these inclusions are probably derived from eosinophils is based on the appearance within macrophages of structures resembling eosinophil granules at various stages of degradation and the similarity between the lattice repeat of the crystalloids and that of the crystalline core of the eosinophil granule. The crystalloid inclusions may be related to the Charcot-Leyden crystals found in human beings.
Insights
Acidophilic macrophage pneumonia, a condition involving crystalloid-laden macrophages, was observed in specific mouse strains. These crystalline inclusions in macrophages may originate from eosinophils, resembling human Charcot-Leyden crystals.
Area of Science:
- Immunology
- Pathology
- Cell Biology
Background:
- Acidophilic macrophage pneumonia is defined by the presence of crystalloid-laden alveolar macrophages.
- This condition has been observed in specific mouse strains, suggesting genetic or environmental factors may play a role.
Purpose of the Study:
- To investigate the characteristics and potential origin of crystalloid inclusions in macrophages associated with acidophilic macrophage pneumonia.
- To compare these inclusions with known crystalline structures in other biological systems.
Main Methods:
- Histological examination of lung tissue from affected mice.
- Ultrastructural analysis of macrophages to characterize the crystalloid inclusions.
- Comparison of crystalloid morphology and lattice structure with eosinophil granules and Charcot-Leyden crystals.
Main Results:
- Acidophilic macrophage pneumonia was identified in NMRI, T x HT, and C57BL mice, but not in CBA or BALB/c mice.
- Histology revealed focal accumulations of eosinophilic macrophages with crystalline cytoplasm, often alongside granulocytes.
- Ultrastructural analysis showed needle-shaped and rhomboidal crystals within macrophages, exhibiting a lattice structure with a 3-5 nm repeat.
- The crystalloid inclusions showed similarities to degraded eosinophil granules and Charcot-Leyden crystals.
Conclusions:
- The crystalloid inclusions in acidophilic macrophage pneumonia likely originate from the breakdown products of granulocytes, particularly eosinophils.
- The observed crystalloids share ultrastructural similarities with Charcot-Leyden crystals found in human conditions.
- These findings provide insights into the pathogenesis of acidophilic macrophage pneumonia and its potential link to eosinophil-related crystalline structures.
