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Processing of engulfed apoptotic bodies yields T cell epitopes
1Divisione di Medicina II/Laboratorio di Immunologia del Tumori, Istituto Scientifico H San Raffaele and Università di Milano, Italy. Bellonem@hsr.it
Journal of Immunology (Baltimore, Md. : 1950)
|April 21, 1998
Summary
This study reveals how macrophages process engulfed apoptotic cells, showing antigen presentation to T cells is crucial for self-tolerance. This clarifies a key mechanism in programmed cell death and immune response.
Area of Science:
- Immunology
- Cell Biology
Background:
- Programmed cell death, or apoptosis, is a fundamental process in multicellular organisms.
- Phagocytic cells, like macrophages, engulf apoptotic cells, but their subsequent fate and immune implications are not fully understood.
Purpose of the Study:
- To investigate the fate of engulfed apoptotic cells within macrophages.
- To determine if antigens from apoptotic cells can be presented by macrophages to T lymphocytes.
Main Methods:
- Tracing the degradation of apoptotic cells within macrophages using microscopy.
- Assessing the recognition and lysis of antigen-presenting macrophages by cytotoxic T lymphocytes (CTLs).
Main Results:
- Engulfed apoptotic cells are initially contained in vacuoles, fragmenting into vesicles over time.
- Antigens from apoptotic cells can associate with macrophage MHC class I molecules.
- Antigen-specific CTLs recognize and lyse macrophages presenting antigens from engulfed apoptotic cells, requiring functional antigen presentation machinery.
Conclusions:
- Macrophages indirectly present antigens from engulfed apoptotic cells, influencing T cell responses.
- This mechanism is vital for establishing self-tolerance, particularly in the absence of danger signals.