IFN-gamma influences the migration of thoracic duct B and T lymphocyte subsets in vivo. Random increase in...

Thoracic duct lymphocytes (TDL) continuously patrol through the body, facilitating immune responses at most sites. IFN-gamma might regulate immune responses by influencing the migration of TDL. Therefore, it was investigated in vivo whether IFN-gamma affects the migration of thoracic duct B, T, CD4+, and CD8+ lymphocytes from blood to lymph. Labeled TDL were injected i.v. into rats continuously receiving IFN-gamma via a central venous catheter. The numbers of B, T, CD4+, and CD8+ lymphocytes were determined in blood and thoracic duct lymph for 120 h. IFN-gamma increased the disappearance of TDL from the blood to a similar extent in all subsets. In contrast, the reappearance of B and T lymphocyte subsets in the lymph was decreased: B lymphocytes were affected significantly more than T lymphocytes, whereas CD4+ and CD8+ lymphocytes were affected to a similar extent. Our study suggests that differential retention within the tissue rather than preferential immigration into the tissue creates a microenvironment with a distinct composition of lymphocyte subsets.