Human CD40-ligand: molecular cloning, cellular distribution and regulation of expression by factors controlling IgE...

Area of Science:

• Immunology
• Molecular Biology

Background:

• CD40-Ligand (CD40-L) is a crucial molecule in immune responses.
• Understanding CD40-L expression is vital for immune system research.

Purpose of the Study:

• To clone the cDNA for human CD40-Ligand (CD40-L).
• To investigate the expression patterns of CD40-L in human peripheral blood mononuclear cells (PBMNC).
• To explore the relationship between CD40-L expression and IgE production.

Main Methods:

• Cloning of human CD40-L cDNA from a CD4-positive T cell clone.
• Northern blot analysis to detect CD40-L mRNA.
• Flow cytometry (FACS) analysis to determine CD40-L protein expression on different cell types.
• Treatment of cells with Interleukin-4 (IL-4) and Interferon-gamma (IFN-γ) to assess their effects on CD40-L expression.

Main Results:

• The deduced amino acid sequence predicted a type II membrane protein of 261 amino acids.
• Human CD40-L was detected on T cells (both CD4+ and CD8+ subsets, including CD45R0+ and CD45RA+), but absent from B cells and monocytes.
• IL-4 upregulated CD40-L mRNA levels, while IFN-γ reduced them.

Conclusions:

• Human CD40-L is expressed on various T cell subsets.
• The expression of CD40-L is modulated by cytokines involved in IgE regulation.
• These findings suggest a correlation between human CD40-L expression and IgE production, highlighting its potential role in allergic responses.