purpose. To assess the effects of mycophenolate mofetil (MMF) therapy on T helper cell activation status, using CD69 expression and cytokine profile with flow cytometry in relation to clinical activity in uveitis.

methods. Patients with posterior or intermediate uveitis treated with MMF (n= 10), patients with active uveitis not treated with MMF and receiving no or minimal therapy (n= 10), and healthy volunteers (n= 21) had peripheral blood lymphocyte immunofluorescence analysis for T helper cell (CD4, CD3) markers, activation status (CD69), and intracellular cytokine (interleukin [IL]-2, interferon [IFN]-γ, and IL-4) levels. Patients were compared before and during MMF therapy in relation to T helper cell activation and clinical activity.

results. Patients with active uveitis not treated with MMF and receiving no or minimal therapy had increased frequency of CD69-positive CD4 T cells (10.5%±4.6%, P= 0.0007) compared with healthy volunteers (3.3%±2.7%). Of all patients receiving MMF therapy, only patients with moderate to severe uveitis activity in the pre-MMF treatment group (n= 5; 15.5%±5.0%, P= 0.004) had increased frequency of CD69-positive CD4 T cells compared with healthy volunteers. During MMF therapy, a significant reduction in frequency of CD69-positive CD4 T cells occurred in patients with prior moderate to severe uveitis activity (to 8.9%±3.8%, P= 0.04). Levels of CD69-positive CD4 T cells in patients who had had inactive or mildly active disease (n= 5) before and during MMF therapy were comparable with levels in healthy volunteers. No significant changes in cytokine levels were found between the patient and control groups. A significant association between changes in frequency of CD69-positive CD4 T cells and changes in visual acuity (P= 0.008) and changes in vitreal haze (binocular indirect ophthalmoscopy score; P= 0.01) was observed in MMF-treated patients with prior moderate to severe uveitis activity.

conclusions. Reduction in uveitis activity during MMF therapy correlates with reduction in frequency of peripheral blood CD69-positive CD4 cells. The frequency of CD69-positive CD4 T cells is a measure of activity in posterior uveitis and may guide adequate immunosuppression.