Fever-range hyperthermia stimulates alpha4beta7 integrin-dependent lymphocyte-endothelial adhesion

Area of Science:

• Immunology
• Cell Biology
• Molecular Medicine

Background:

• Lymphocyte homing to lymphoid tissues is crucial for immune responses.
• L-selectin and alpha4beta7 integrin are key adhesion molecules mediating lymphocyte migration.
• Febrile temperatures are known to dynamically regulate L-selectin-mediated adhesion.

Purpose of the Study:

• To investigate the direct effects of fever-range hyperthermia on alpha4beta7 integrin function.
• To determine if hyperthermia enhances lymphocyte adhesion to lymphoid tissues.
• To elucidate the molecular mechanisms underlying hyperthermia-induced changes in lymphocyte adhesion.

Main Methods:

• In vitro treatment of murine TK1 lymphoma cells and human peripheral blood lymphocytes (PBL) with fever-range hyperthermia (40°C, 12h).
• Assessment of alpha4beta7 integrin-dependent adhesion to high endothelial venules (HEV) in frozen lymphoid tissue sections.
• Utilized function-blocking antibodies against alpha4beta7 integrin and MAdCAM-1 to confirm involvement.
• Analyzed alpha4beta7 integrin expression and aggregation.

Main Results:

• Fever-range hyperthermia significantly stimulated alpha4beta7 integrin-dependent adhesion of TK1 cells and PBL to HEVs.
• Adhesion was confirmed to involve alpha4beta7 integrin and its ligand, MAdCAM-1.
• Hyperthermia promoted alpha4beta7 integrin-mediated cell aggregation but did not alter cell surface expression levels.
• No enhancement of alpha4beta7 integrin adhesion to fibronectin was observed.

Conclusions:

• Fever-range hyperthermia directly enhances the adhesive function (avidity) of alpha4beta7 integrin on lymphocytes.
• This enhanced avidity contributes to increased lymphocyte homing to lymphoid tissues.
• The findings suggest a mechanism by which fever amplifies immune cell trafficking and potentially enhances immune surveillance and response.