The effect of the
photosensitizer merocyanine 540 (
MC 540) on platelets and on three marker viruses was examined to assess its potential in reducing virus transmission by blood products. The results demonstrated several deleterious effects of
MC 540 (4-24 micrograms/mL) on platelet morphology and function in both the absence and presence of light (450-600 nm). Treatment of washed platelets with
MC 540 in the dark resulted in a significant release of
serotonin in the absence of added agonist, as well as a diminished response to
thrombin as measured in vitro. In addition,
photosensitization caused
spontaneous platelet aggregation and release of 92 percent of the releasable
serotonin without the addition of an agonist. Because photo-treatment of blood products is likely to be performed in a
protein-rich medium, the influence of
albumin on the phototoxic effects on platelets was assessed.
Albumin added to the
suspension medium at concentrations greater than or equal to 1.0 percent protected the platelets against the effects of
MC 540 in the dark, whereas 5-percent
albumin was required for protection against the phototoxic effects of
MC 540 on the platelet response to
thrombin. The
antiviral activity of
MC 540 and light was examined by using the
lipid-containing viruses herpes simplex virus (HSV) and bacteriophages phi 6 and PM2. Of the
lipid-enveloped viruses, HSV was 25 times more photosensitive to
MC 540 than was phi 6 (15 micrograms/mL). PM2, which has an internal
lipid layer, was almost 300 times less sensitive to
MC 540 and light than was HSV.(ABSTRACT TRUNCATED AT 250 WORDS)