Photodynamic Therapy-Induced Immune Modulation: Part III

This study is designed as a double-blinded proof of concept of feasibility study to define if the immunosuppression associated with photodynamic therapy (PDT) can be blocked by treatment with cyclo-oxygenase-2 (COX-2) inhibitor celecoxib in comparison to placebo. PDT consists of application of the photosensitizer 5-aminolevulinic acid followed by treatment with a blue light. PDT is used to treat pre-cancerous actinic keratosis on large areas of skin. These studies are a continuation of ongoing studies that indicate that the lipid mediator platelet-activating factor (PAF) is generated in skin following PDT, and that PDT suppresses the immune system. It is hypothesized that PDT-generated PAF results in the immunosuppression associated with PDT. Therefore, it is proposed that a treatment to block that immunosuppression could protect the patient undergoing PDT. Blockers of the PAF system are not currently commercially available. However research studies done at Wright State University using mice indicate that PAF- and PDT-induced immunosuppression is blocked by treatment with COX-2 inhibitors. This study is conducted as a proof of concept. Study length and visit for subjects with actinic keratoses: The first part of the study is completed in 12 days then there are follow up visits at 6 and 12 months. There are a total of 6 separate visits to the research office. Study length and visit for control subjects: The study is completed in 10 days. There are a total of 4 separate visits to the research office.