Introduction to Lymphocyte Recirculation – Lymphocyte Recirculation and Homing

Let us explore lymphocyte recirculation and homing. So why do lymphocytes recirculate around the body? Well, lymphocytes collectively have millions of different antigen specific receptors - the B-cell receptor on the surface of the B-lymphocyte, the T-cell receptor on the surface of the T-lymphocyte. And therefore, for each antigen specificity, there are only initially a small number of T-cells and B-cells. Also the adaptive response requires dendritic cells in order to activate naïve T-cells. It needs helper T-cells. And it needs the cognate B-cells, that is B-cells with the same antigen specificity as the T-cells to interact with each other. Lymphocytes therefore need to seek out their antigen, they need to travel around the body to find antigen. So they recirculate through the blood, the lymph nodes, the efferent lymphatics, and then eventually back to the blood circulation. Meanwhile dendritic cells can pick up antigen in the tissues and migrate via the afferent lymphatics to the local draining lymph nodes....