Immunological effects of photodynamic therapy in the treatment of actinic keratosis and squamous cell carcinoma.

The use of photodynamic therapy is extensive, due to its antitumoral, antibacterial and photorejuvenation effects. It destroys tumor via direct cell destruction and indirectly via vascular shutdown, induction of acute local inflammatory response and activation of the immune system. Both innate and adaptive immune cells are involved in the immunological effects of photodynamic therapy. In addition to UV-induced DNA damage, inflammation and immunosuppression are also essential elements in the pathogenesis of actinic keratosis. Both immunosuppression induced by UV and defective immune response to dysplastic keratinocytes may be the target of photodynamic therapy to eliminate actinic keratosis. These elements are discussed in the present review, highlighting the possible mechanism of photodynamic therapy to effectively treat actinic keratosis.

Sensitization of immune cells following hexylaminolevulinate photodynamic therapy of cervical intraepithelial neoplasia.

BACKGROUND: Effects of photodynamic therapy (PDT) were tested with respect to immune cell stimulation in cervical intraepithelial neoplasia (CIN). METHODS: A patient with CIN received hexaminolevulinate (HAL) and subsequent PDT. These data were compared to a placebo PDT patient and a healthy HPV16-vaccinated donor. Isolation of peripheral blood mononuclear cells (PBMC) was performed before PDT and at 4 different time points after PDT. The proliferation of these PBMC was tested by [3H]thymidine incorporation following stimulation with control or HPV16-L1 peptides. Potential effects on the CD4+ and CD8+ cell subsets were analysed. RESULTS: The data revealed an unchanged or decreased proliferation of HPV16-L1 peptide-stimulated PBMC as compared to placebo patient. HPV16-L1 peptide incubation of PBMC from the HAL patient demonstrated significant proliferative capacity after PDT. The CD4+ and CD8+ T cell populations in placebo patient were slightly increased after HPV16-L1 peptide administration at each time point. Mixed results were obtained for CD4+ cells as compared to controls and nearly unchanged amounts of CD8+ cells were detectable following HPV16-L1 peptide exposure of PBMC from the HAL/PDT-treated patient. CONCLUSIONS: These findings suggest a T cell reaction from CIN patients during repeated HAL/PDT treatment. However, further immune cell populations might be involved during PDT.

Urinary excretion of porphyrins is increased in patients with HIV-1 infection.

Urine concentrations of total porphyrins and of porphyrin precursors, delta-aminolaevulinic acid and porphobilinogen, were analysed in the first-morning urine samples of 36 people with established HIV-1 infection. For comparison, we also analysed the urine samples of 26 healthy HIV-seronegative people. In patients with HIV-1 infection concentrations of total porphyrins were found to be significantly higher than in healthy controls. Furthermore, there was a close correlation between concentrations of total porphyrins and porphobilinogen and urine neopterin concentrations in patients. Our data indicate an association between chronic immune activation and altered porphyrin metabolism. The data may provide a rationale for the observation of acute porphyria in patients with HIV-1 infection.