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Interference of a human leukocyte interferon preparation with stimulatory activities in leukocyte-conditioned medium
Abstract:
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.
Insights
Human leukocyte interferon inhibits the production of growth factors in phytohemagglutinin-conditioned leukocyte medium (PHA-LCM). This interference prevents the growth of essential human bone marrow stem cells and their precursors.
Area of Science:
- Hematology
- Immunology
- Cell Biology
Background:
- Leukocyte-conditioned medium (LCM) is crucial for hematopoietic progenitor growth.
- Phytohemagglutinin-activated LCM (PHA-LCM) supports multilineage hematopoietic stem cell growth.
- The role of interferons in PHA-LCM production is not fully understood.
Purpose of the Study:
- To investigate the effect of human leukocyte interferon on PHA-LCM's ability to support hematopoietic progenitor growth.
- To characterize the molecular changes in PHA-LCM induced by interferon.
Main Methods:
- PHA-LCM was prepared with and without human leukocyte interferon.
- Gel filtration (Sephacryl S-300), affinity chromatography, and gel electrophoresis were used for characterization.
- Stimulatory activity on hematopoietic stem cells (CFU-gemm), committed precursors (CFU-c), and erythroid precursors (BFU-e) was assessed.
Main Results:
- PHA-LCM without interferon exhibited a peak stimulating pluripotent stem cells (CFU-gemm) and committed precursors (CFU-c, BFU-e).
- PHA-LCM prepared with 1000 U/ml of interferon showed altered elution profiles on gel filtration.
- The interferon-treated PHA-LCM lacked growth-promoting activities for hematopoietic progenitors.
Conclusions:
- Human leukocyte interferon abolishes the stimulatory activity of PHA-LCM.
- Interferon may reduce the production of essential growth-promoting molecules.
- Interferon interferes with molecular events necessary for hematopoietic progenitor colony formation.