Hypersensitivity of Lymphocytes from Chronic Lymphocytic Leukemia Patients to Ultraviolet Light-C Radiation

Abstract

Chronic lymphocytic leukemia (CLL) results in the accumulation of mature immunologi-cally defective lymphocytes in GO phase. Lymphocytes from CLL patients were exposed to UVC radiation to determine whether these cells are capable of undergoing apoptosis, as a response to DNA damage. Lymphocytes from CLL patients were found to be readily killed by ultraviolet light-C (UVC) radiation. Cells from healthy donors were minimally affected by doses of UVC ten times higher then those which caused dramatic drops in the metabolism of CLL cells. At four hours after irradiation, the reduction of 3–(4,5-dimethylthia-zol-2-yl)-2,5-diphenyl tetrazoliurn bromide (MTT) had dropped by 50% for CLL cells exposed to a dose of 10 J/m². In contrast, there was no significant drop for healthy cells exposed to 100 J/m². Cell death was measured by trypan blue staining, flow cytometry of Annexin V-PI stained cells, and Wright staining. By 24 hours after irradiation, significant amounts of cell death were observed in CLL cells at doses which had no significant effects on viability of healthy lymphocytes. The extreme sensitivity of CLL lymphocytes to UVC indicates that phototherapy should be explored as a potential treatment for this neoplasm.

Key Words:

• chronic lymphocytic leukemia
• UVC
• PARP
• Deoxyribonucleosides
• cell death