Monoclonal antibodies specific for interleukin 3-sensitive murine cells

Area of Science:

• Immunology
• Hematology
• Molecular Biology

Background:

• Interleukin-3 (IL-3) is a critical cytokine for hematopoietic stem cell proliferation and differentiation.
• Identifying the IL-3 receptor is essential for understanding hematopoietic regulation and developing targeted therapies.

Purpose of the Study:

• To characterize the molecule recognized by monoclonal antibodies CC11 and CB5.
• To investigate the role of this molecule in IL-3-dependent cellular processes.

Main Methods:

• Utilized 18 IL-3-dependent cell lines and primary cells from fetal liver and bone marrow.
• Performed immunoprecipitation and Western blotting to determine molecular weight and isoelectric point.
• Assessed antibody effects on cell proliferation and cytokine-mediated responses.
• Investigated IL-3 modulation of cell surface glycoprotein expression.

Main Results:

• Monoclonal antibodies CC11 and CB5 bind to a 50,000-70,000 Mr glycoprotein present on IL-3-dependent cells, including hematopoietic stem and progenitor cells.
• This glycoprotein is absent on cells insensitive to IL-3 and non-hematopoietic tissues.
• CC11 and CB5 specifically inhibit IL-3-driven cell proliferation without affecting responses to other cytokines or mitogens.
• Recombinant IL-3 modulates the expression of this glycoprotein on IL-3-dependent cells.
• Cells expressing the CC11/CB5 glycoprotein proliferate in response to IL-3, while those lacking it do not.

Conclusions:

• The CC11/CB5 reactive molecule is a functional receptor for mouse IL-3.
• This finding provides a novel target for studying and potentially manipulating IL-3 signaling in hematopoiesis.