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Endocytic routes of exogenous antigen in murine dendritic cells and macrophages
1Department of Cell Biology, Second Military Medical University, Shanghai 200433, China.
Objective:
To compare the endocytic routes of exogenous antigen between murine dendritic cells (DCs) and macrophages (M phi s).
Methods:
Murine bone marrow-derived DCs and peritoneal M phi s were pulsed with horseradish peroxidase (HRP)-5 nm colloidal gold for 10 minutes, then grouped and chased for 0-120 minutes in culture medium. Intracellular distribution of 5 nm colloidal gold was explored by means of the cellular enzymatic-chemistry of acid phosphatase and MHC II immuno-cytochemistry under electron microscope.
Results:
After 10 minutes of pulse with HRP-5 nm colloidal gold and 30 minutes of chase, most HRP-5 nm gold particles internalized by DCs entered into MHC class II compartments (M II Cs), and a small portion entered into acid phosphatase-positive lysosomes. In contrast to DCs, most M phi s lysosomes were accessed by HRP-5 nm gold particles, and a small portion of HRP-5 nm gold particles entered into M II Cs. After 60 minutes of chase, 5 nm gold particles could hardly be seen within M phi s, whereas most 5 nm gold particles were still retained in DCs.
Conclusions:
The endocytic route of exogenous antigen in DCs seems to be different from that in M phi s. Antigens taken by M phi s mainly enter into lysosomes within 30 minutes. In the case of DCs, most internalized antigens enter into M II Cs, which may be related to their unique antigen-presenting function. In addition, M phi s seem to have more powerful capacity to scavenge exogenous antigen than DCs.
Insights
Dendritic cells (DCs) internalize exogenous antigens into MHC class II compartments, while macrophages (M phi s) direct them to lysosomes. Macrophages show a greater capacity for antigen scavenging than DCs.
Area of Science:
- Immunology
- Cell Biology
- Endocytosis
Background:
- Dendritic cells (DCs) and macrophages (M phi s) are crucial antigen-presenting cells.
- Understanding their distinct endocytic pathways is vital for immune response modulation.
Purpose of the Study:
- To elucidate and compare the endocytic routes of exogenous antigens in murine DCs and M phi s.
- To investigate the intracellular trafficking of internalized antigens.
Main Methods:
- Bone marrow-derived DCs and peritoneal M phi s were incubated with HRP-5 nm colloidal gold.
- Intracellular distribution was analyzed using acid phosphatase and MHC II immuno-cytochemistry via electron microscopy.
- Cells were chased for varying time points (0-120 minutes) post-pulsing.
Main Results:
- DCs primarily directed internalized gold particles to MHC class II compartments (M II Cs) within 30 minutes.
- Macrophages predominantly channeled gold particles to lysosomes, with fewer entering M II Cs.
- Macrophages showed reduced particle retention over time compared to DCs, suggesting faster degradation or efflux.
Conclusions:
- Murine DCs and M phi s exhibit distinct endocytic pathways for exogenous antigens.
- DCs utilize M II Cs for antigen processing, potentially linked to their antigen-presenting role.
- M phi s prioritize lysosomal pathways and demonstrate a higher capacity for antigen scavenging.