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Monoclonal antibody EBM11 (anti-CD68) discriminates between dendritic cells and macrophages after short-term culture
M G Betjes1, M C Haks, C W Tuk
1Department of Cell Biology, Free University, Amsterdam, The Netherlands.
Insights
Distinguishing dendritic cells (DCs) from macrophages (M phi) is challenging. A novel method using the EBM11 marker reveals distinct cellular localization in DCs versus M phi, improving identification.
Area of Science:
- Immunology
- Cell Biology
Background:
- Dendritic cells (DCs) and macrophages (M phi) are antigen-presenting cells often confused due to similar MHC class II expression.
- Lack of specific markers hinders accurate discrimination between DCs and M phi.
Purpose of the Study:
- To identify a specific marker for distinguishing human dendritic cells (DCs) from macrophages (M phi).
- To investigate the cellular localization of the EBM11 (anti-CD68) marker in DCs and M phi.
Main Methods:
- Immunohistochemistry using the EBM11 (anti-CD68) antibody.
- Light and electron microscopy.
- Analysis of cells before and after short-term culture.
Main Results:
- EBM11 reactivity shows distinct localization: a juxtanuclear spot in DCs versus diffuse cytoplasmic staining in M phi.
- The EBM11 spot in DCs is observed after short-term culture, a common DC enrichment step.
- Before culture, DCs and M phi are morphologically and marker-wise indistinguishable.
Conclusions:
- EBM11 provides a reliable method to differentiate human DCs from M phi.
- The lysosomal apparatus structure plays a significant role in distinguishing these antigen-presenting cells.
- Suggests a close relationship between M phi and DCs, with potential functional implications.
Abstract:
Identification of dendritic cells (DC) is usually done on the basis of their strong MHC class II expression, their typical dendritic morphology and their capacity to induce a strong proliferation of allogeneic T cells. However using these criteria DC can easily be confused with MHC class II positive macrophages (M phi). In addition, the lack of an antibody directed to a specific DC marker greatly hampers the discrimination between DC and M phi. In the present study it is shown that EBM11 (anti-CD68) is a marker specific for both human M phi and DC but in a distinctive way. Human DC locate the EBM11 reactivity in a discrete juxtanuclear spot in contrast to M phi which show EBM11 reactivity throughout the cytoplasm. This greatly improves identification of DC. Light and electron microscopy showed that the CD68 epitope is associated with (phago-)lysosomes. Remarkably the EBM11 spot was only seen in DC after short-term culture, which is an essential step in all classical DC enrichment procedures. Before culture, M phi and DC were indistinguishable. These results show the close relationship between M phi and DC and suggest an important role for the structure of the lysosomal apparatus in these antigen-presenting cells.
