Repair of cyclobutane pyrimidine dimers in unstimulated human mononuclear cells is deficient at very low fluences of ultraviolet B and is not enhanced by addition of deoxyribonucleosides.


Journal Article

Unstimulated human T lymphocytes are exquisitely sensitive to UVB irradiation. This hypersensitivity appears to relate to low deoxyribonucleotide pool sizes. They have also been reported to be defective in global excision of cyclobutane pyrimidine dimers, but such experiments may have been carried out at supralethal doses, where unrepaired excision breaks persist indefinitely. We use a T4 endonuclease Comet assay to show that removal of cyclobutane pyrimidine dimers is defective in the unstimulated mononuclear cell fraction (mainly T lymphocytes) even at sublethal fluences from an FS20 broad spectrum UVB lamp. Moreover, removal is not enhanced by addition of deoxyribonucleosides to the medium. Cells which are failing to remove cyclobutane pyrimidine dimers readily form fresh incision breaks in response to a second UVB fluence, indicating that they retain repair capacity and suggesting that removal of types of damage other than cyclobutane pyrimidine dimers is effective.

Full Text

Cited Authors

  • Han, P; Clingen, PH; Lowe, JE; Katsuya, A; Arlett, CF; Green, MH

Published Date

  • July 1998

Published In

Volume / Issue

  • 13 / 4

Start / End Page

  • 353 - 356

PubMed ID

  • 9717171

Pubmed Central ID

  • 9717171

Electronic International Standard Serial Number (EISSN)

  • 1464-3804

International Standard Serial Number (ISSN)

  • 0267-8357

Digital Object Identifier (DOI)

  • 10.1093/mutage/13.4.353


  • eng