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Updated: Aug 16, 2026
Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages
Published on: April 20, 2018
Ultrastructural changes of alveolar macrophages of protein-deficient rats
Abstract:
Enhancement of phagocytosis of alveolar macrophages (AM) was examined by cytochemical and electron microscopic studies on macrophages from protein-deficient rats. The macrophages from rats fed on 5% casein diet had longer microvilli, more phagocytic vacuoles and more lysosomes with acid phosphatase activity than those from control rats. Many phagocytic vacuoles were seen close to the site of attachment of opsonized sheep red blood cells (SRBC) and were mainly located in the subplasmalemmal layer which was rich in microfilaments but contained few cytoplasmic organelles. After attachment, opsonized SRBC were engulfed through a hemispherical crater into the phagocytic vacuoles. The phagocytic vacuoles seemed to be formed by invagination of the cell surface because they had membrane ATPase activity continuous with that of the outer surface of the plasma membrane. In the cell, the vacuoles fused with the numerous preexisting lysosomes in the interior of the cell receiving the contents of the latter. The mechanism of enhancement of phagocytosis in protein-deficiency is discussed.
Insights
Protein deficiency enhances the phagocytic activity of alveolar macrophages (AM). These macrophages exhibit increased microvilli, phagocytic vacuoles, and lysosomes, improving their ability to engulf pathogens.
Area of Science:
- Immunology
- Cell Biology
- Nutrition Science
Background:
- Alveolar macrophages (AM) play a crucial role in lung immunity.
- Nutritional status significantly impacts immune cell function.
- Protein deficiency is a global health concern affecting immune responses.
Purpose of the Study:
- To investigate the effect of protein deficiency on the phagocytic capacity of alveolar macrophages.
- To elucidate the ultrastructural and cytochemical changes in macrophages from protein-deficient rats.
Main Methods:
- Cytochemical and electron microscopy techniques were employed.
- Macrophages were isolated from rats fed a 5% casein diet (protein-deficient) and control rats.
- Phagocytosis of opsonized sheep red blood cells (SRBC) was analyzed.
Main Results:
- Protein-deficient macrophages displayed enhanced phagocytosis compared to controls.
- Increased microvilli, phagocytic vacuoles, and acid phosphatase-rich lysosomes were observed.
- Phagocytic vacuoles formed via cell surface invagination and fused with lysosomes.
Conclusions:
- Protein deficiency enhances alveolar macrophage phagocytosis through structural and functional adaptations.
- Increased lysosomal activity and efficient phagosome formation contribute to improved pathogen clearance.
- Dietary protein intake is critical for maintaining optimal macrophage immune function.
