Immunohistochemical evidence of specific iris involvement in blau syndrome

Purpose: To evaluate iris involvement in Blau syndrome using histology and immunohistochemistry. Methods: Iridectomy specimen of a patient with treated Blau syndrome and a normal control were evaluated by light microscopy and immunohistochemistry using antibodies against CD4⁺, CD8⁺, HLA-DR, CD68⁺, NF-κB and IL-17. Results: Blau iris tissue demonstrated increased numbers of CD4⁺ lymphocytes and CD68 negative, HLA-DR positive spindle shaped cells compared to normal iris tissue. Blau iris tissue also demonstrated elevated CD4⁺/CD8⁺ ratio and IL-17 and NF-κB immunolabeling. No macrophages, epithelioid cells, or granulomas were noted in the Blau specimen. Conclusions: The persistent immunolocalization of inflammatory markers in an iris specimen from an aggresively treated patient with proven Blau syndrome suggests that further pathologic and immunohistochemical investigation of Blau ocular tissue is necessary to better understand the complexities of NOD2 activating mutations in the eye.