Isolated epithelioid cells from disaggregated BCG granulomas - an ultrastructural study

Area of Science:

• Immunology
• Cell Biology
• Pathology

Background:

• Epithelioid cells are key components of granulomas, but their morphology and differentiation are not fully understood.
• Non-caseating granulomas can be induced experimentally for cellular investigation.

Purpose of the Study:

• To characterize the ultrastructural morphology of epithelioid cells within induced granulomas.
• To investigate the changes in epithelioid cell morphology during granuloma development.
• To explore the potential differentiation pathway of epithelioid cells.

Main Methods:

• Induction of non-caseating granulomas in rats via subcutaneous injection of BCG vaccine.
• Isolation of epithelioid cells using collagenase digestion.
• Ultrastructural analysis of epithelioid cells from intact granulomas and cell suspensions at different time points (4, 10, 28 days).

Main Results:

• Epithelioid cells exhibited a morphological spectrum, including plasmacytoid and vesicular forms, with intermediate stages.
• The proportion of vesicular epithelioid cells increased with granuloma maturation.
• A full spectrum of morphologies was observed as early as 4 days post-induction.

Conclusions:

• Mononuclear phagocytes may differentiate into vesicular epithelioid cells through a plasmacytoid intermediate stage within granulomas.
• The study provides a method for isolating viable epithelioid cells for further functional studies.
• Morphological plasticity of epithelioid cells suggests dynamic changes during granuloma formation and resolution.