An application of linear output error modelling for studying lymphocyte migration in peripheral lymphoid tissues

Lymphocyte recirculation between lymphatic and blood vessels and migration through tissues are essential mechanisms underlying immunological surveillance. However, the kinetics of lymphocyte migration through lymphoid tissues remains poorly understood. The present study of lymphocyte migration, based on a sheep model and entailing the long term cannulation of blood vessels and lymphatic vessels efferent from lymph nodes, represents the first attempt to apply control engineering based models to overcome some of the experimental impediments to understanding the complex phenomena involved in lymphocyte migration. An output error model order (1,2,nk) was systematically selected under given criteria from four classes of Linear Time-Invariant Single-Input Single-Output (LTI-SISO) systems to represent the peripheral lymph node system. The unit impulse responses were simulated under noise free conditions and their features were extracted to describe the dynamics of the system. The findings from this study revealed novel information about several aspects of the dynamics of lymphocyte migration.