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SEM morphological studies of phagocytosis by rat macrophages and rabbit polymorphonuclear leukocytes
Abstract:
Peritoneal rat macrophages and rabbit polymorphonuclear leukocytes were obtained after thioglycollate or glycogen stimulation. Optimal conditions for phagocytosis were determined by a recently developed quantitative fluorimetric assay. We studied by serial SEM micrographs macrophages and polymorphonuclear leukocytes incubated either in medium or in the presence of different types of phagocytic particles. We compared the morphological aspects of adsorption and phagocytic processes for opsonized microorganisms (Micrococcus lysodeikticus and Candida albicans) with these for inert beads of iron and metallic mercury. Without phagocytosis, in the presence of fresh homologous serum, we observed a progressive development of microvilli or lamellipodia in ruffles and by the end, hypertrophied ruffles appeared at one pole of the cell. We noted extremely well developed ruffles during phagocytosis of opsonized microorganisms. These were practically absent on the macrophages incubated with inert particles. The mean number of adsorbed particles is more elevated in the case of iron and metallic mercury beads than for microorganisms. The rate of ingestion of inert particles was considerably higher than for microorganisms even when they were opsonized. In conclusion, at all stages of the phagocytic process, we observe different morphological features of the macrophages depending on the nature of the phagocytosed particles.
Insights
Phagocytosis in macrophages and polymorphonuclear leukocytes differs morphologically based on particle type. Inert particles are ingested faster than microorganisms, despite different adsorption rates.
Area of Science:
- Cell Biology
- Immunology
Background:
- Phagocytosis is a critical cellular process for immune defense and cellular homeostasis.
- Macrophages and polymorphonuclear leukocytes are key phagocytic cells involved in pathogen clearance.
Purpose of the Study:
- To investigate the morphological differences in phagocytosis by macrophages and polymorphonuclear leukocytes when interacting with various particles.
- To compare the adsorption and ingestion of opsonized microorganisms versus inert particles.
Main Methods:
- Utilized peritoneal rat macrophages and rabbit polymorphonuclear leukocytes stimulated with thioglycollate or glycogen.
- Employed a quantitative fluorimetric assay to determine optimal phagocytosis conditions.
- Conducted serial scanning electron microscopy (SEM) to observe cellular morphology during particle interaction.
Main Results:
- Distinct cellular ruffling patterns were observed: well-developed ruffles during microorganism phagocytosis, but absent with inert particles.
- Higher adsorption rates were noted for inert iron and mercury beads compared to microorganisms.
- Ingestion rates were significantly higher for inert particles than for opsonized microorganisms.
Conclusions:
- The nature of phagocytosed particles significantly influences the morphological characteristics of macrophages and polymorphonuclear leukocytes during phagocytosis.
- Cellular response and efficiency vary depending on whether the target is a microorganism or an inert particle.