Inhibition of Human Lymphocyte Stimulation by Visible Light and Phthalocyanine Photosensitization: Mitogen and Wavelength Dependency

Abstract

Mitogenic stimulation of human peripheral blood lymphocytes is inhibited by phthalocyanine photosensitization using visible light. The mechanism of inhibition was studied using stimulating agents differing in their mode of action. Stimulation by the plant lectin phytohemagglutinin (PHA) was the least sensitive to inhibition by photosensitization, followed by the tumor promoter phorbol myristate acetate (PMA) and the calcium ionophore A23187. Mitogenic stimulation could also be inhibited by light only, but higher fluences were needed. The order of efficacy was blue greater than red greater than green light, and the response to A23187 was least affected, followed by an increased inhibition of the response to PHA and PMA stimulation. Possible targets and mechanisms for these effects are discussed.

Photodynamic sterilization of red cells and its effect on contaminating white cells: viability and mechanism of cell death

“…Previously, the effect of PDT with AlPcS 4 on isolated lymphocytes was described. It was found that the mitogenic activity of lymphocytes was inhibited in a dose‐dependent fashion, and subsequently this activity was shown to be wavelength and mitogen dependent 28,29 . In the present study, the effects of virucidal treatment using two phthalocyanines on the viability of various WBC populations was determined.…”

PRECLINICAL EXAMINATION OF FIRST and SECOND GENERATION PHOTOSENSITIZERS USED IN PHOTODYNAMIC THERAPY

“…The majority of these studies have focused on: (a) synthesis and initial evaluation of new photosensitizers; (b) identification of subcellular targets involved in PDT cytotoxicity; (c) evaluation and comparison of photosensitizer localiza1.ion and cytotoxicity for normal and malignant cells,; (d) defining in vivo treatment parameters associated with PDT toxicity; (e) determining normal tissue responses following PDT; and (f) documenting in vivo targets and systemic responses associated with PDT. For a comprehensive background on various PDT topics examined over the past 8-10 years, the reader may wish to scan previous Yearly Reviews written by Kessel (1984), Moan (1986), Spikes (1986), Dougherty (1987), Sieber (1987), Girotti (1990) and Rosenthal (1991). Additional background material on PDT can also be obtained from s,pecific books edited by Kessel and Dougherty (1'983), Doiron and Gomer (1984), Andreoni and Cubeddu (1984), Kessel (1985), Jori and Perria (1985), Gomer *Abbreviations: BPD, benzoporphyrin derivative; ET2, etiopurpurin; HP, hematoporphyrin; HPD, hematoporphyrin derivative; H S V , Herpessimplex virus; LDL, low density lipoprotein; MC-540, merocyaniine 540; NMR, nuclear magnetic resonance; NPe6, mono-I-aspartyl chlorin e6; NT2, octaethylpurpurin; O,, singlet oxygen; PC, phthalocyanine; PDT, photodynami'c therapy; RIF, radiation induced fibrosarcoma.…”

Letter to the Editor

“…White light can modify the response of human cells to stimuli (e .g . Kol et al 1989), as well as UV light, suggesting that further investigation of this phenomenon may be worthwhile .…”