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Expression of a nonclassical MHC class Ib molecule in the eye
J Y Niederkorn1, E Y Chiang, T Ungchusri
1Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Transplantation
|December 28, 1999
Summary
MHC class Ib molecule Qa-2 is expressed in the eye, including the anterior chamber. This finding suggests Qa-2 may play a role in maintaining immune privilege within the eye.
Area of Science:
- Immunology
- Ophthalmology
Background:
- MHC class Ia molecules are scarce in the anterior chamber, an immune-privileged site.
- This scarcity may protect against T cell injury but increase vulnerability to NK cell attack.
- MHC class Ib molecules, like Qa-2, may have similar functions to class Ia.
Purpose of the Study:
- To investigate the expression and distribution of the MHC class Ib molecule Qa-2 in the eye.
- To determine if Qa-2 contributes to the immune-privileged status of the anterior chamber.
Main Methods:
- Analyzed Qa-2 mRNA transcription using RNase protection and RT-PCR.
- Determined Qa-2 protein expression via immunohistochemistry, flow cytometry, and ELISA.
- Monitored Qa-2 expression in resting and interferon-gamma-stimulated eye cells.
Main Results:
- Detected membrane-bound and soluble Qa-2 isoforms in various eye tissues, including anterior chamber cells.
- Confirmed Qa-2 expression on corneal epithelium and endothelium, iris ciliary bodies, and retina.
- Found Qa-2 expression to be inducible by interferon-gamma and absent in lens cells.
Conclusions:
- MHC class Ib molecules (Qa-2) are expressed by ocular cells.
- Qa-2 expression in the anterior chamber suggests a role in immune privilege.