Isolation and identification of apoptosis inducing nucleosides from CD57(+)HLA-DRbright natural suppressor cell line.

The CD57(+)HLA-DRbright natural suppressor (57.DR-NS) cell line derived from human decidual tissue generated the apoptosis in K562/Molt4 target cells mediated by soluble factors released into the culture supernatant. The factors in the culture fluid of the 57. DR-NS cell line were isolated by the physicochemical procedures as follows, first by a preparative octadecyl sorbent column, further by thin-layer-chromatography (TLC), finally by reverse-phase high-performance liquid chromatography (HPLC). The six major components (P1-P6) obtained by HPLC demonstrated the generation of apoptotic cell death of target cells. The physicochemical characters of six active components were strongly suggested to be nucleosides and their modified forms in nature. Then, the physicochemical structures of the six active components were finally determined by fast atom bombardment-mass spectrometry (FAB-MS) and nuclear magnetic resonance (1H NMR) spectrometry as follows: P1, 2'-deoxyuridine; P2, ribothymidine; P3, 2'-O-methyluridine; P4, thymidine; P5, 2'-O-methylinosine; P6, 2'-O-methylguanosine. Thus, we collectively named them "apoptosis inducing nucleosides (AINs)." Then, we demonstrated that the induction of apoptosis in target cells by the 57.DR-NS cell line was mediated by a series of AINs.