Hyaluronan binding identifies the most proliferative activated and memory T cells.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• CD44 is a cell surface receptor expressed on T cells, crucial for regulating T cell function.
• The interaction between CD44 and hyaluronan is a key aspect of T cell behavior during immune responses.
• Understanding the dynamics of hyaluronan binding in T cells is essential for deciphering immune cell activation and memory formation.

Purpose of the Study:

• To investigate the timing and conditions under which T cells bind to hyaluronan.
• To determine the characteristics of T cells that exhibit hyaluronan binding post-activation.
• To explore the role of hyaluronan binding in T cell proliferation and memory development.

Main Methods:

• Utilized fluoresceinated hyaluronan to detect binding on murine T cells.
• Stimulated T cells in vitro and in vivo with specific antigens to induce activation.
• Analyzed hyaluronan binding in conjunction with cell proliferation markers and memory phenotype markers (e.g., CD122, CD44, CD62L).
• Investigated the effect of cytokines like IL-7 and IL-15 on hyaluronan-binding T cells.

Main Results:

• Naïve T cells do not bind hyaluronan, but binding is induced upon antigen-specific activation.
• Hyaluronan binding is observed on proliferating T cells, correlating with the strength of the activation stimulus.
• A subset of activated T cells with a memory phenotype (CD122(+) CD44(hi)) retained hyaluronan binding.
• Hyaluronan-binding memory T cells showed increased proliferation in response to IL-7 and IL-15.
• In vivo, 20-30% of antigen-specific CD8(+) memory T cells bound hyaluronan, enriching for central memory cells (CD62L+).
• Homeostatic proliferation in vivo also induced hyaluronan binding on rapidly dividing cells.

Conclusions:

• Hyaluronan binding is an inducible characteristic of activated and memory T cells.
• This binding serves as a marker for highly proliferative T cells within activated and memory populations.
• Hyaluronan binding may play a role in the expansion and maintenance of T cell memory.