['To explore the efficacy of the modified extracorporeal photochemotherapy (ECP) in improving the apoptotic rate of lymphocytes in vitro.', 'The spleens which were obtained from liver transplantation donor under aseptic condition were used as experimental materials. Splenic lymphocytes (SPs) suspensions were prepared by modified and traditional ECP method, respectively. And then the isolated SPs were treated by the irradiation of 8-methoxypsoralen (8-MOP) combined with ultraviolet A (UVA) named PUVA, 8-MOP and UVA, and compared with a blank group meanwhile. The treated SPs were cultured overnight in an incubator at 37 Degrees Celsius, in a humidified atmosphere of 50 mL/L CO2 for 6-8 hours. The morphological changes of cells were observed using an inverted microscope, the apoptotic rates of SPs were detected by flow cytometry, and the difference between groups was analyzed finally.', 'The apoptotic rate at early stage and the total apoptotic rate of SPs prepared by the modified ECP method were respectively (95.33±3.03)% and (97.10±2.12)% after treated by PUVA, (23.39±4.55)% and (36.32±6.63)% after treated by 8-MOP, and (66.98±3.60)% and (68.65±4.35)% by UVA. Compared with control group (12.82±1.86% and 13.4±2.65%), there were statistically significant differences (P<0.01). The apoptotic rate at early stage and the total apoptotic rate of SPs prepared by the traditional ECP method were respectively (79.73±4.21)% and (82.70±4.13)%, (61.42±2.28)% and (68.91±2.18)%, (19.30±1.78)% and (28.06±1.88)%, (10.84±0.98)% and (12.77±1.22)%, and the statistical comparisons between groups also had significant difference (P<0.01). In addition, there was a significant difference in the early and total apoptosis between the modified and traditional ECP (P<0.01), but no obvious variation in the end-stage apoptosis in the two groups (P>0.05).'] Does [ The modified extracorporeal photochemotherapy promote apoptosis of spleen lymphocytes ]?