Purging Effect Of IFN-α And IL-2 Activated Bone Marrow Cells On Leukemi A Cells And Preliminary Studies On The Cytotoxicity Mechanisms

Autologous bone marrow transplantation (ABMT ) is an alternative effective treatment for acute leukemias. In comparison with allogeneic BMT ,the relapse risk post—ABMT is higher because of contaminated leukemic cells in graft and lack of graft versus leukemia (GYL) effect. IL— 2 activated bone marrow (AMB) cells have purging effect on leukemic cells, and GVL can be induced by IL —2 after ABMT. IFN—αenhances the killing potential of IL —2 activated lymphocytes for tumor cells. The cytotoxic mechanisms of activated lymphocytes are being actively investigated in the world,but not yet in china. We studied in vitro the purging effects of IFN —α and IL —2 ABM cells,the maintenance of the effects by IL—2 in combination with IFN —α and the cytotoxic purging mechanisms of activated lymphocytes.The results were as follows: .1. IFN — α significantly augmented the cytotoxicity of IL—2 ABM cells at 1 day culture (P <0. 001),and had no effect on the cytotoxicity at 3 day culture. The bone marrow cytotoxicity induced by IFN —α alone was comparable with that by IL —2 at 1 day culture,and significantly lower than that by IL —2 at 3 day culture.2. When K.562 cells were co—cultured with bone marrow cells in the presence of IL —2 for 3 days ,the leukemic cells were markedly eradicated by 1. 2—3. 3 logs. K562 cell killing was increased by 0. 45 — 2.66 logs when cultured with IL — 2 in combination with IFN —α(p<0.001). Il-2 alone or in combination with IFN —α had no inhibition of CFU—GM and K562 cells.3. Compared with IL —2 or IFN —α alone,the combination of the two cytokines maintained more effectively the cytotoxic potential of ABM cell against tumor cells.4. The peripheral mononuclear cells (PMNC) cocultured with tumor cells were exposed to IL — 2 or IFN—α alone or in combination, CD4+CD8+ subset increased to over 2.0%,the IL — 2Rα and its mRNA of the PMNC were up—regulated, and the proportion of CD2— and CD11a— positive cells were increased.5. IL —2 in combination with IFN—α enhanced lymphocytes cocultured with K562 cells to secrete TNF—α and IFN —γ,but had no effects on IL —2 production.6. IFN — α or IL — 2 had no effects on the expression of granzyme A and B in lymphocytes, and IL —2 slightly induced the expression of granzyme B mRNA. Perforin activity in the lymphocytes was increased after one day exposure to IFN —α or IL —2, and the activity was enhanced when exposed to the combination of IL — 2 and IFN —α(P<0. 05). The regulation of perforin mRNA expression by IL — 2 or IFN —α was similar to that of perforin activity by either...