Abstract
Purpose: :
Graves orbitopathy (GO) is an immunologic disease that is predominantly T-cell mediated. Identifying surface antigens on the inflammatory cells in orbital tissue of GO patients could help identify potential targets for immunotherapy.
Methods: :
After appropriate IRB approval, orbital fat specimens from 9 orbits of 7 patients with GO undergoing orbital decompression and 5 control patients without Graves disease undergoing blepharoplasty were obtained. Paraffin embedded specimens were stained with hematoxylin and eosin and immunostained with antibodies to CD2 (a T-cell marker), CD20 (a B-cell marker), and CD25 (IL-2 receptor). Specimens were graded by 2 pathologists for cellularity and staining intensity (none, trace, 1-4+).
Results: :
Among 7 GO patients (3 women and 4 men), the mean age was 49.7 years. Among 5 control blepharoplasty patients (4 women, 1 man), the mean age was 73.5 years. The GO patients did not differ significantly from the blepharoplasty patients in terms of age or gender (p>0.05). Two of nine GO specimens were devoid of inflammatory cells and showed no immunostaining. CD2 showed trace staining in 5 of 5 control specimens, trace staining in 5 of 9 GO specimens, and 1+ staining in 2 of 9 GO specimens. CD20 showed trace staining in 1 of 5 control specimens and 1+ staining in 3 of 9 GO specimens. CD25 showed trace staining in 3 of 5 control specimens and trace staining in 6 of 9 GO specimens.
Conclusions: :
CD20 was present in some GO tissues, suggesting possible B-cell involvement in GO. These findings may provide justification for the investigational use of rituximab, an anti-CD20 monoclonal antibody, in GO. Daclizimab, an anti-CD25 antibody, may also be useful in GO. Orbital fat is not the ideal tissue to assess for inflammatory cell surface antigens due to the limited number of inflammatory cells present even in active disease. Extraocular muscle tissue may be more useful but is less readily available for study. Blepharoplasty fat explants serve as a useful but imperfect control as this tissue too can show signs of chronic inflammation and necrosis. Further study with a larger number of patients and additional cell markers, particularly T-cell markers such as CD52, may be useful to identify additional targets for therapy.
Keywords: immunohistochemistry • orbit