Patch testing in patients treated with systemic immunosuppression and cytokine inhibitors

Background: Currently, there is little data available on the reliability of patch testing in patients taking immunosuppressive agents other than systemic corticosteroids. Objectives: We present data from 38 patients who were patch tested whilst taking various immunomodulating agents to determine if positive reactions can be elicited. Patient/materials/methods: Between September 2006 and May 2009, 38 patients attending the St John's Institute of Dermatology were patch tested whilst taking immunosuppressive agents including azathioprine, ciclosporin, infliximab, adalimumab, etanercept, methotrexate, mycophenolate mofetil, and tacrolimus. Results: Positive patch test reactions of varying degrees and significance were elicited in: 2 of 10 patients on azathioprine; 5 of 11 patients on ciclosporin; 1 patient on ciclosporin and Fumaderm®; 1 patient on infliximab; 1 patient on infliximab and methotrexate; 1 of 2 patients on adalimumab; 1 patient on etanercept and methotrexate; 3 of 4 patients on methotrexate; 1 of 3 patients on mycophenolate mofetil; and 1 patient on mycophenolate mofetil and tacrolimus. Negative patch test reactions occurred in 1 patient on azathioprine and ciclosporin; 1 patient on infliximab and azathioprine; and 1 patient on mycophenolate and ciclosporin. Conclusions: Positive patch test reactions can be elicited in patients taking azathioprine, ciclosporin, infliximab, adalimumab, etanercept, methotrexate, mycophenolate mofetil, and tacrolimus. However, it remains unclear what effect these immunosuppressive drugs may have on suppressing allergic patch test reactions and further studies should be carried out to determine the reliability of testing in these circumstances.