Dov Stekel, Claire Parker and Martin Nowak present a mathematical mode
l of T-cell recirculation between blood, spleen and the lymphatic syst
em. Comparison with classical experiments on lymphocyte recirculation
and localization demonstrates that simple kinetics are sufficient to e
xplain lymphocyte homeostasis between these organs, and that T-cell co
unts in blood are highly sensitive to changes in the recirculation par
ameters.