ABSTRACT
Introduction 204 Lymphocyte recirculation and lymph node structure 204 Four main lymph node tissue compartments 205 Migration of recirculating lymphocytes into and within 205
lymph nodes T and B cell recruitment into immune responses 206
in lymph nodes CD4 T cell priming, differentiation, and dispersal 206 B cell interaction with antigen and primed T cells 206 The two types of T-dependent antibody response 206 Extrafollicular antibody responses 207 Germinal center formation 207 A working hypothesis for germinal center function 208
Other features of lymph nodes 209 Marginal zones in lymph nodes 209 CD8 T cell responses in lymph nodes 209 Lymph node development 210 Structure and functions of the spleen 210 The white pulp structure 210 The red pulp structure 211 Immune responses in the spleen 211 Immature B cell selection in the spleen 211 Concluding remarks 212 Key points 212 References 212
Lymphocytes respond specifically to infection by proliferating and differentiating into immunological effectors, such as helper T cells, plasma cells, and cytotoxic lymphocytes. The proliferation of lymphocytes during immune responses can be very rapid and constraints on this growth are critical. Further, control of the specificity of the lymphocytes that are induced to become effectors affords protection from infection, while minimizing the chance of inducing autoimmunity or allergy.
