The identification, characterization, and distribution of guinea pig CCR4 and epitope mapping of a blocking antibody

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Th2 lymphocytes are key in allergic inflammation.
• CCR4 is a chemokine receptor expressed on Th2 cells.
• CCR4 is also found on T lymphocytes producing Th1 cytokines.

Purpose of the Study:

• Investigate the function of CCR4 in guinea pig (gp) T lymphocytes.
• Identify the guinea pig CCR4 (gpCCR4) sequence.
• Determine the role of gpCCR4 in T cell migration and trafficking.

Main Methods:

• Identified the open-reading frame of gpCCR4.
• Transfected cells with gpCCR4 and assessed migration towards CCR4 ligands.
• Used anti-human CCR4 monoclonal antibody (10E4) to detect surface CCR4 expression.
• Analyzed CCR4 expression in peripheral blood, thymus, lung, and bronchoalveolar lavage fluid.
• Studied chimeric chemokine receptors to understand antibody binding.

Main Results:

• gpCCR4 encodes a 361-amino acid protein with high homology to human and murine CCR4.
• Transfected cells migrated towards CCR4 ligands (macrophage-derived chemokine and thymus and activation-regulated chemokine).
• CCR4 was detected on 12% of peripheral blood T helper cells and low numbers of thymocytes.
• CCR4(+) T helper cells were abundant in normal lung (9%) and bronchoalveolar lavage fluid (52%).
• The antibody 10E4 inhibits gpCCR4 responses and recognizes its amino terminus.

Conclusions:

• CCR4 plays a significant role in T lymphocyte development and trafficking in guinea pigs.
• CCR4 expression is elevated in the lung and bronchoalveolar lavage fluid, suggesting involvement in pulmonary immune responses.
• The anti-CCR4 antibody 10E4 is a functional inhibitor and recognizes the N-terminus of gpCCR4.