Human thymocytes express CCR-3 and are activated by eotaxin

Area of Science:

• Immunology
• Cell Biology

Background:

• Eotaxin is a chemokine primarily known for eosinophil activation.
• Constitutive expression of eotaxin mRNA has been observed in the thymus.
• The eotaxin receptor, CCR-3, is present on thymocytes.

Purpose of the Study:

• To investigate the presence and function of eotaxin and its receptor CCR-3 in the thymus.
• To determine the effects of eotaxin on thymocyte activation and chemokine secretion.

Main Methods:

• Immunohistochemical analysis to localize eotaxin expression in the thymus.
• Flow cytometry to detect CCR-3 expression on thymocytes.
• Equilibrium binding assays using radiolabeled eotaxin.
• In vitro assays to assess eotaxin-induced thymocyte migration, calcium mobilization, and chemokine secretion.

Main Results:

• Eotaxin expression was localized in the medulla and Hassle's corpuscles of the thymus.
• CCR-3 was detected on thymocytes, particularly on CD8 single-positive cells.
• Eotaxin binding to thymocytes was consistent with CCR-3 interaction.
• Eotaxin stimulated thymocyte migration, calcium mobilization, and secretion of IL-8, RANTES, and MIP-1beta.

Conclusions:

• Eotaxin and its receptor CCR-3 are present and functional in the thymus.
• Eotaxin plays a role in thymocyte activation and chemokine release.
• These findings suggest physiological implications for eotaxin in lymphocyte mobilization within the thymus.