Comparison of sensitivity to ultraviolet B irradiation between human lymphocytes and hematopoietic stem cells

To investigate the clinical applicability of prophylaxis of post-transplant graft-versus-host disease by UV-B irradiation of stem cell preparations, t he UV-B sensitivities of human lymphocytes and primitive hematopoietic prog enitors were compared. The mononuclear cell fractions (MNC) derived from hu man cord blood and granulocyte-colony-stimulating factor-mobilized peripher al blood were used. After UV-B irradiation, lymphocyte proliferation abilit y, hematopoietic colony-forming cells, and apoptotic cells were analyzed. A t a dose of 33 J/m(2), significant differences were observed in the residua l percentages of hematopoietic progenitors and lymphocyte functions [ANOVA, F (5,46)=19.4; P<.0001], and the difference between CFU-C (85.2% + 24.0%; n = 8) and MLR (12.7% + 12.6%; n = 10) was significant (P <.0001). There we re no significant differences in the residual percentages of CFU-C, HPP-CFC , and LTC-IC, Percentages of annexin V-positive cells in the total MNC and the CD34(+) cell population in MNC after UV-B irradiation were 69.8% and 18 .7%, respectively. In conclusion, there was a range of UV-B doses over whic h T lymphocytes were inactivated but hematopoietic progenitors, including H PP-CFC and LTC-IC, were preserved.(Blood. 2000;96:2632-2634) (C) 2000 by Th e American Society of Hematology.