اثر بهاركنندگي DNA آزادشده از سلول سرطاني ميلوييد انسان )HL-06( بر ري تكثير لنفوسيت هاي خون محيطي

Growth inhibition of Secreted DNA of human myeloid cell line(HL-60) on peripheral blood lymphocyte

Background and purpose: So far many protein factors capable of inhibiting the immune system are secreted by different cancer cell lines in the culture supernatant and characterized. In this report, the release of DNA fragments into the culture supernatant of human promyelocytic cell line, HL-60, with immunosuppressive activity was investigated. Materials and methods : HL-60 culture supernatant was concentrated and applied to ion-exchange DEAE-Sepharose CL-6B column. The column was eluted with NaCl gradient and the fractions were collected for assay. Fractions with immunosuppressive activity were purified with HPLC. Result: The data show that trypsin and RNase have no effect on antiproliferation, but DNase destroyed the immunosuppressive activity. The DNA with irreversible immunosuppressive activity was found to be double-stranded with the molecular weight range between 0.6 and 1.5 kilobases. This DNA did not change the cell number and viability and as a result was not cytotoxic. Cell cycle analysis has suggested that DNA molecule could arrest the mitogen-stimulated lymphocytes in G1 phase, and prevent the cells from entering into the proliferating S phase. Conclusion: These data show that DNA like immunosuppressive proteins could inhibit the proliferation of lymphocytes as well as the proliferation of some cancer cells.