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Proceedings Paper

Photodynamic immune modulation (PIM)
Author(s): John R. North; David W. C. Hunt; Guillermo O. Simkin; Leslie G. Ratkay; Agnes H. Chan; Harvey Lui M.D.; Julia G. Levy
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Paper Abstract

Photodynamic Therapy (PDT) is accepted for treatment of superficial and lumen-occluding tumors in regions accessible to activating light and is now known to be effective in closure of choroidal neovasculature in Age Related Macular Degeneration. PDT utilizes light absorbing drugs (photosensitizers) that generate the localized formation of reactive oxygen species after light exposure. In a number of systems, PDT has immunomodulatory effects; Photodynamic Immune Modulation (PIM). Using low- intensity photodynamic regimens applied over a large body surface area, progression of mouse autoimmune disease could be inhibited. Further, this treatment strongly inhibited the immunologically- medicated contact hypersensitivity response to topically applied chemical haptens. Immune modulation appears to result from selective targeting of activated T lymphocytes and reduction in immunostimulation by antigen presenting cells. Psoriasis, an immune-mediated skin condition, exhibits heightened epidermal cell proliferation, epidermal layer thickening and plaque formation at different body sites. In a recent clinical trial, approximately one-third of patients with psoriasis and arthritis symptoms (psoriatic arthritis) displayed a significant clinical improvement in several psoriasis-related parameters after four weekly whole-body PIM treatments with verteporfin. The safety profile was favorable. The capacity of PIM to influence other human immune disorders including rheumatoid arthritis is under extensive evaluation.

Paper Details

Date Published: 17 September 1999
PDF: 5 pages
Proc. SPIE 3863, 1999 International Conference on Biomedical Optics, (17 September 1999); doi: 10.1117/12.364340
Show Author Affiliations
John R. North, QLT PhotoTherapeutics, Inc. (Canada)
David W. C. Hunt, QLT PhotoTherapeutics, Inc. (Canada)
Guillermo O. Simkin, QLT PhotoTherapeutics, Inc. (Canada)
Leslie G. Ratkay, QLT PhotoTherapeutics, Inc. (Canada)
Agnes H. Chan, QLT PhotoTherapeutics, Inc. (Canada)
Harvey Lui M.D., Vancouver Hospital/Univ. of British Columbia (Canada)
Julia G. Levy, QLT PhotoTherapeutics, Inc. (Canada)

Published in SPIE Proceedings Vol. 3863:
1999 International Conference on Biomedical Optics
Qingming Luo; Britton Chance; Lihong V. Wang; Steven L. Jacques, Editor(s)

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