Classification of lymphocytes recirculating in the spleen

Area of Science:

• Immunology
• Lymphocyte Biology
• Splenic Microcirculation

Background:

• Understanding lymphocyte trafficking is crucial for immune response.
• The spleen's extravascular lymphoid tissues (ELTs) are key sites for immune cell interaction.
• Lymphocyte subpopulations exhibit distinct migratory patterns.

Purpose of the Study:

• To investigate the recirculation patterns of lymphocyte subpopulations within the spleen.
• To determine if specific lymphocyte types, like Null cells, home to splenic ELTs.
• To elucidate the behavior of lymphocytes in a normothermic ex vivo spleen perfusion model.

Main Methods:

• Utilized a closed-circuit normothermic perfusion system for pig spleens.
• Washed blood cells from spleens before perfusion.
• Introduced autologous blood lymphocytes labeled with fluorescein isothiocyanate (FITC) into perfusions.

Main Results:

• Recirculating lymphocytes rapidly established equilibrium with splenic extravascular lymphoid tissues.
• Splenic emigrants showed an absence of Null cells and reduced weakly E-rosetting cells.
• Fluorescently labeled Null cells were enriched in the perfusate, indicating they do not home to splenic ELTs.

Conclusions:

• Null cells are likely nonrecirculating lymphocytes.
• The spleen's marginal zones concentrate recirculating lymphocytes.
• Differential recirculation of lymphocyte subpopulations influences their distribution within the spleen.