ANTITUMOR-ACTIVITY OF HUMAN UMBILICAL-CORD BLOOD-CELLS - A COMPARATIVE-ANALYSIS WITH PERIPHERAL-BLOOD AND BONE-MARROW

Although the hematopoietic reconstituting ability of human umbilical c ord blood cells (UCBC) is well documented, their antitumor cytotoxic p otential has not been well studied. Therefore, UCBC were compared to n ormal peripheral blood stem cells (PBSC) and bone marrow (BM) stem cel l harvests for cytomorphology. antitumor cytotoxic activity before and Lifter ex vivo cytokine manipulation, response to T and B cell mitoge ns, expression of adhesion molecules and immunophenotypes using flow c ytometry, cytokine production and iii vivo antitumor activity. BM and PBSC. but not UCBC, did not form cellular clusters in culture. More cy totoxic granules were present in the cytoplasm of UCBC than PBSC follo wing activation in vitro. Ex vivo manipulation of UCBC with cytokines produced more cytotoxicity to K562 and Raji tumor cells than PBSC or B M (p < 0.001). Most cytotoxic cells in UCBC cultures were T lymphocyte s. and a correlation existed between the number of CD56(+) cells and c ytotoxicity levels, particularly after in vitro activation with interl eukin-2. No significant difference in adhesion molecule expression was noted among UCBC. PBSC and BM cells. However, there was a significant ly decreased expression of CD54 molecules (ICAM) on UCBC compared to P BSC (p < 0.05). IL-2 activated UCBC showed significant antitumor effec ts against K562 leukemic cells grown in SCID mice. Thus UCBC contained more antitumor effector cells and precursors than cells from marrow o r peripheral blood cells which might be capable of providing a therape utic effect.