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CD68 antigen expression by human retinal pigment epithelial cells.
S G Elner1, V M Elner, J C Nielsen
1Department of Ophthalmology, University of Michigan, Ann Arbor 48105.
Experimental Eye Research
|July 1, 1992
Summary
Retinal pigment epithelium (RPE) cells express CD68, a marker typically found on mononuclear phagocytes. This finding suggests RPE cells share immunophenotypic similarities with macrophages, aiding in their identification in vitro.
Area of Science:
- Immunology
- Cell Biology
- Ophthalmology
Background:
- The retinal pigment epithelium (RPE) primarily phagocytizes aged photoreceptor outer segments.
- RPE cells may also phagocytize particulates via receptors found on mononuclear phagocytes.
- CD68 is a glycoprotein expressed by mononuclear phagocytes, used for their identification.
Purpose of the Study:
- To investigate the expression of CD68 in human retinal pigment epithelium (RPE) cells.
- To determine if CD68 can serve as an antigenic marker for RPE cells in vitro.
Main Methods:
- Immunohistochemistry was performed on freshly isolated RPE cells, primary RPE cultures, and RPE cell lines using a panel of CD68 monoclonal antibodies (mAbs).
- Reactivity was assessed in RPE cells at various passages and after stimulation with interferon-gamma.
- Control experiments used control mAbs and mouse serum.
Main Results:
- Freshly isolated RPE cells showed CD68 reactivity in a small percentage of cells (5%).
- Primary RPE cultures and all 12 RPE cell lines exhibited uniform and strong CD68 staining, persisting up to passage 40.
- Interferon-gamma stimulation did not alter CD68 staining patterns.
Conclusions:
- Human RPE cells constitutively express CD68.
- This expression supports immunophenotypic similarities between RPE cells and mononuclear phagocytes.
- CD68 serves as a reliable antigenic marker for identifying RPE cells in vitro.