Interference of a human leukocyte interferon preparation with stimulatory activities in leukocyte-conditioned medium for human hematopoietic stem cells.
Medium conditioned by leukocytes in the presence of phytohemagglutinin (PHA-LCM) promotes the growth of multilineage hemopoietic progenitors derived from human bone marrow. However, PHA-LCM prepared in the presence of a human leukocyte interferon preparation does not support mixed colony formation. Crude PHA-LCM preparations were characterized by gel filtration, affinity chromatography, and gel electrophoresis. The elution profile on Sephacryl S-300 of PHA-LCM prepared without interferon showed a distinct peak that stimulated the growth of pluripotent stem cells (CFU-gemm) and committed precursors (CFU-c, BFU-e). Gel filtration of PHA-LCM, prepared with 1000 U/ml of interferon, revealed a change in the elution profile. The eluted material demonstrated no growth-promoting activities. We conclude that the abolished stimulatory activity of PHA-LCM, prepared with human leukocyte interferon, might be due to a reduced production of stimulatory molecules, suggesting that interferon interferes with the molecular events required for colony formation of committed and noncommitted hemopoietic progenitors.
D002455:Cell Division; D003114:Colony-Forming Units Assay; D003470:Culture Media; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D007962:Leukocytes / Q000502:physiology*; D010835:Phytohemagglutinins / Q000494:pharmacology
D003470:Culture Media; D007370:Interferon Type I; D010835:Phytohemagglutinins