Em. Procaccini et al., IN-VITRO PHOTOINHIBITION BY PSORALEN AND ULTRAVIOLET-A RADIATION OF HUMAN HEMATOPOIETIC PROGENITORS, Photodermatology, photoimmunology & photomedicine, 12(5), 1996, pp. 200-203
The in vitro sensitivity of human hematopoietic progenitors to PUVA, 8
-MOP and UVA alone was investigated. 8-MOP alone at final concentratio
ns of 150, 200, 600 and 1000 ng/ml did not modify colony growth of cir
culating and bone marrow erythroid (BFU-E), myeloid (CFU-GM) and immat
ure (CFU-GEMM) hematopoietic progenitors obtained from normal controls
. The exposure of the same progenitors to increasing doses of UVA, up
to 12 J/cm(2), progressively decreased hematopoietic colony growth (wi
th estimated 50% inhibition occurring at about 5 J/cm(2)). In vitro PU
VA treatment (8-MOP 200 ng/ml followed by UVA 5 J/cm(2)) caused 90% gr
owth inhibition of circulating and bone marrow hematopoietic progenito
rs. In addition, the treatment completely inhibited the formation of s
pontaneous erythroid colonies, obtained from 5 polycythemic patients,
that an considered to be a marker of this neoplastic disease. PUVA cyt
otoxicity was assessed by the colorimetric MTT assay. The percentage o
f cell death after PUVA exposure was 29+/-10% for both peripheral and
bone marrow mononuclear cells. Our findings indicate that 8-MOP alone
is not toxic to hematopoietic progenitors whereas WA treatment determi
nes in vitro a dose-dependent inhibition of the clonogenic capacity of
normal hematopoietic cells. PUVA treatment enhances this effect, caus
ing a quite complete inhibition of hematopoietic progenitors colony fo
rmation from normal donors and spontaneous BFU-E colony formation from
polycythemic patients.