CCR7-mediated migration in the thymus controls γδ T-cell development

Area of Science:

• Immunology
• T-cell biology
• Developmental immunology

Background:

• Gamma delta (γδ) T-cell development and intrathymic migration are less understood compared to alpha beta (αβ) T cells.
• Thymic localization is known to influence T-cell development, but its specific role in γδ T-cell differentiation requires further investigation.

Purpose of the Study:

• To investigate the impact of thymic localization, mediated by C-C chemokine receptor (CCR)7 and CCR9, on γδ T-cell development.
• To determine if defects in thymic localization lead to cell-intrinsic migration issues affecting γδ T-cell populations.

Main Methods:

• Generation of C-C chemokine receptor (CCR)7- and CCR9-deficient mice on a TcrdH2BeGFP reporter background.
• Bone marrow (BM) transfer experiments into irradiated wild-type recipients.
• Intrathymic labeling to monitor recent thymic emigrants.
• In vitro assessment of γδ T-cell development from precursor cells.
• Immunohistology to analyze cell localization within the thymus.

Main Results:

• CCR7 deficiency led to decreased γδ T-cell frequencies and numbers, and reduced thymic output.
• CCR9 deficiency resulted in increased γδ T-cell frequencies and numbers.
• CCR7 and CCR9 expression were critical for γδ T-cell localization in the thymic medulla and cortex, respectively.
• γδ T-cell motility was not affected by CCR7 or CCR9 deficiency, suggesting localization, not motility, is the primary defect.

Conclusions:

• Proper intrathymic localization, regulated by CCR7 and CCR9, is essential for normal γδ T-cell development and homeostasis.
• Defects in chemokine receptor expression disrupt the precise migration patterns required for γδ T-cell maturation within the thymus.