GENERATION OF ANTIGEN-PRESENTING CELLS FOR SOLUBLE-PROTEIN ANTIGENS EX-VIVO FROM PERIPHERAL-BLOOD CD34(-PATIENTS() HEMATOPOIETIC PROGENITORCELLS IN CANCER)

Peripheral blood CD34(+) hematopoietic progenitor cells (PBPC) mediate hematopoietic reconstitution in cancer patients after autologous tran splantation and can be expanded ex vivo in the presence of colony-stim ulating factors. This study shows that functionally active antigen-pre senting cells (APC) for soluble proteins are generated and expanded in these PBPC cultures. CD34(+) cells were cultured ex vivo in medium co ntaining stem cell factor, interleukin-1 beta (IL-1 beta), IL-3, IL-6, and erythropoietin (EPO). The cells from these cultures developed int o very potent APC of tetanus toxid and purified derivative of tubercul in for autologous T cells in vitro. The antigen-presenting capacity of those cells was maintained for at least 38 days of culture. These APC resembled immature cells of the myelomonocytic cell lineage by surfac e marker, immunocytochemistry and ultrastructural analysis. Such APC m ight be able to present antigens from certain tumors to the immune sys tem.