HLA-antigens in the human uvea.

With the use of monoclonal antibodies in an indirect immunofluorescence technique we studied the distribution of Class I (HLA-ABC and B27) and Class II (HLA-DR) antigens in the human uvea. W6/32, directed against the core of HLA-ABC antigens, was used to study the distribution of Class I antigens. The anterior border layer of the iris, the non-pigmented and pigmented epithelium and the external basement membrane of the ciliary body and the vascular endothelium in the uvea showed a positive staining for Class I antigens. B27/M1, directed against an epitope of the HLA-B27 antigen, and the control antibody A11/Aw24, which was directed against an epitope of HLA-A11, revealed the same distribution pattern in respectively HLA-B27 and HLA-A11 positive donor eyes. The intensity of their staining was much weaker than the staining with W6/32. Class II antigens were studied with OkIa1, an antibody directed against the core of HLA-DR antigens. HLA-DR antigens were detectable on single cells scattered throughout the entire uvea. These cells did not seem to relate to any anatomical entity. No staining for Class II antigens was seen in the uveal blood vessel endothelium. The expression of HLA-antigens in the uvea is compatible with the distribution in other tissues. These findings suggest that the expression of HLA-B27 in the human uvea does not explain why the eye is one of the target tissues in HLA-B27 associated disease.