Extracorporeal photochemotherapy does not suppress T- or B-cell responses to novel or recall antigens

Background: Extracorporeal photopheresis (ExP) is an effective therapy for several conditions including cutaneous T-cell lymphoma, scleroderma, and al lograft rejection. Experimental animal models suggest that ExP may induce a ntigen-specific immunosuppression. Objective: Our purpose was to determine the effect of photopheresis on humo ral and cell-mediated immunity in human subjects. Methods: Recall and primary immune responses of patients with scleroderma r eceiving monthly ExP treatments were assessed by delayed type hypersensitiv ity skin tests, T-cell proliferative responses after immunizations with tet anus toroid and keyhole limpet hemocyanin, and serum antibody titers agains t common viral pathogens. Results: After 6 months of ExP: viral antibody titers and delayed type hype rsensitivity responses were not significantly different from baseline value s in all 7 patients tested. T-cell responses to tetanus toroid remained nor mal in 3 of 3 patients tested for a minimum of 6 months after booster immun ization. Immunization with the protein antigen keyhole limper hemocyanin af ter initiation of ExP therapy resulted in sustained T-cell proliferative re sponses up to 6 months in 3 of 3 patients. Conclusion: These results, along with the observation of no increased incid ence of opportunistic infections or neoplasms, suggest that ExP is not broa dly immunosuppressive and does not prevent primary responses to vaccination or other antigenic challenges.