Characterization of granulocyte colony-stimulating factor receptor expressed on human lymphocytes

Area of Science:

• Immunology
• Cell Biology

Background:

• The granulocyte colony-stimulating factor receptor (G-CSFR) plays a crucial role in hematopoiesis.
• Understanding G-CSFR expression on lymphocytes is important for immune system regulation.

Purpose of the Study:

• To characterize G-CSFR expression and function on human lymphocytes.
• To investigate G-CSFR mRNA isoforms in T and B cells.

Main Methods:

• Two-colour and triple-colour immunofluorescence studies to detect G-CSFR expression on B cell subsets.
• G-CSF binding assays on lymphocytes.
• Proliferation assays on T- and B-cell lines stimulated with G-CSF.
• Sequence analysis of G-CSFR mRNA isoforms.

Main Results:

• G-CSFR expression was detected on approximately 25-33% of peripheral B lymphocytes.
• G-CSFR+ B cells were more prevalent in bone marrow and cord blood than in peripheral blood, spleen, and tonsil.
• G-CSFR expression was higher on surface IgD-positive (sIgD+) B cells and found on naive and germinal-center B cells, but not memory B cells.
• Activated T lymphocytes, but not resting T cells, exhibited G-CSF binding.
• T- and B-cell lines expressed functional G-CSFR, as G-CSF enhanced their proliferation.
• G-CSFR was derived from class I and class IV mRNA in T and B cells.

Conclusions:

• G-CSFR is constitutively expressed on the surface of human B lymphocytes, with varying levels across different tissues and subsets.
• G-CSFR expression is inducible on human T lymphocytes upon activation.
• The presence of functional G-CSFR on T and B cells suggests a role for G-CSF in modulating lymphocyte responses.