In vitro assay for phototoxic chemicals

Area of Science:

• Toxicology
• Photobiology
• Cell Biology

Background:

• Chemicals can cause photosensitivity, leading to adverse skin reactions upon light exposure.
• Accurate identification of photosensitizing chemicals is crucial for safety assessment.
• Existing methods for detecting photosensitizers can be resource-intensive.

Purpose of the Study:

• To evaluate an in vitro assay for assessing the photosensitizing potential of chemicals.
• To compare the phototoxicity of known photosensitizers and non-photosensitizers.
• To determine the optimal cell type for this phototoxicity assay.

Main Methods:

• Human lymphoid cells were exposed to UVA and sometimes UVB radiation in the presence of various chemicals.
• Phototoxicity was quantified by measuring the incorporation of 3[H]-thymidine into nuclear DNA.
• Peripheral blood mononuclear cells and a T lymphoblastoid cell line were compared as target cells.

Main Results:

• All tested known photosensitizers exhibited phototoxicity in the assay.
• Non-photosensitizing agents were generally not phototoxic, with retinoic acid as a notable exception.
• The T lymphoblastoid cell line demonstrated superior convenience, cost-effectiveness, and reproducibility compared to peripheral blood mononuclear cells.

Conclusions:

• The in vitro assay effectively distinguishes between photosensitizing and non-photosensitizing chemicals.
• The T lymphoblastoid cell line is a suitable and efficient model for phototoxicity testing.
• This assay shows promise as a predictive tool for identifying novel phototoxic agents.