HEMATOPOIETIC POTENTIAL OF IL-2-CULTURED PERIPHERAL-BLOOD STEM-CELLS FROM BREAST-CANCER PATIENTS

Patients receiving autologous transplants for various malignancies gen erally experience an increased incidence of relapse compared with pati ents receiving unmanipulated allogeneic transplants, We initiated a pr otocol for IL-2 activation of peripheral blood stem cells (PBSC) for i nduction of in vitro and in vivo autologous graft-versus-tumor (GVT) a ctivity in patients with breast cancer, In this study we analyzed the effects of 24 h of IL-2 incubation on the hematopoietic potential of P BSC from these patients, Cells collected by leukapheresis were first c ryopreserved and stored in liquid nitrogen, then thawed rapidly and in cubated with IL-2 in a serum-free system for 24 h, with samples analyz ed before and after incubation. Although there was a significant drop in mononuclear cells (MNC) (from 4.5 to 3.7 x 10(8)/kg) and CD34(+) ce lls (from 12.3 to 7.5 x 10(6)/kg) after 24 h in culture, there was no significant change in colony-forming units (CFU) (from 12.5 to 11.5 x 10(5)/kg), Time to engraftment (neutrophils: < 0.5 x 10(9)/l; platelet s: > 20 x 10(9)/l) was comparable to a cohort of similar patients rece iving non-cultured PBSC transplants, These results indicate that mobil ized frozen/thawed PBSC which have been cultured in IL-2 for 24 h reta in adequate potential for hematopoietic reconsistution in this group o f patients.