Systemic suppression of the contact hypersensitivity by the products of protoporphyrin IX photooxidation.

Photodynamic therapy (PDT) is frequently accompanied by induction of systemic immunosuppression. Photochemical mechanisms underlying this effect are not completely understood. Here, we demonstrate the immunosuppressive activity of photooxidation products of protoporphyrin IX dimethyl ester (PPIX) in a murine model of contact hypersensitivity (CHS) to 2,4-dinitrofluorobenzene (DNFB).

Modulation of delayed type hypersensitivity in mice treated with photoproducts of various photosensitizers used in photodynamic therapy.

Photodynamic therapy is frequently accompanied by the induction of immunosuppression. The photochemical mechanisms behind the induction of this immunosuppression are not clear. The purpose of this study was to evaluate the potential of photoproducts of merocyanine 540 (MC540), protoporphyrin IX (PPIX) and hematoporphyrin derivative (HpD) to cause modulation (suppression/activation) of the T cell immune response in vivo.