Modeling Migration, Compartmentalization and Exit of Naive T Cells in Lymph Nodes Without Chemotaxis

The migration of lymphocytes through secondary lymphoid organs was believed to be mainly controlled by chemokine gradients. This theory has recently been called into question since naive lymphocytes observed in vivo by two-photon microscopy show no evidence of directed migration. We have constructed a simple mathematical model of naive T cell migration in lymph nodes that is solely based on local mechanisms. The model was validated against findings from histological analysis and experimentally determined lymphocyte recirculation kinetics. Our results suggest that T cell compartmentalization in lymph nodes can be explained without long-range chemokine gradients. However, the T cell residence time predicted by our model is significantly lower than observed in vivo, indicating the existence of a mechanism which alters the T cell random walk over time.