Characterization of complementary DNA clones encoding the rabbit IL-8 receptor

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Interleukin-8 (IL-8) is a key proinflammatory cytokine acting as a neutrophil chemoattractant.
• Human IL-8 Receptor (IL-8R) cDNA clones were recently identified.
• Structural similarity between human IL-8R and a rabbit FMLP receptor isoform suggested potential cross-reactivity.

Purpose of the Study:

• To determine the ligand specificity of the rabbit FMLP receptor.
• To confirm if the rabbit FMLP receptor binds IL-8.
• To characterize the rabbit IL-8R.

Main Methods:

• Isolation and characterization of cDNA clones encoding the rabbit receptor.
• Expression of rabbit cDNA clones in mammalian cells.
• Assessment of IL-8 and FMLP binding affinities (Kd).
• Measurement of intracellular Ca2+ concentration changes in response to IL-8 and FMLP.

Main Results:

• Expressed rabbit cDNA clones demonstrated high-affinity IL-8 binding (Kd = 3.6 nM).
• No detectable binding of FMLP was observed.
• IL-8 induced a transient increase in intracellular Ca2+, while FMLP did not.
• The previously reported rabbit FMLP receptor sequence differs by 23 amino acids from the identified rabbit IL-8R sequence.

Conclusions:

• The rabbit FMLP receptor is confirmed to be the rabbit IL-8R.
• The rabbit IL-8R does not bind FMLP, refuting its classification as an FMLP receptor isoform.
• This study clarifies the identity and function of the rabbit IL-8R.