ABSTRACT
Stimulation on Glass ...........................................................................99 5.3 CD19 Is Regulated by the Tetraspanin Network .......................................... 100
5.3.1 CD19 Exists in Preformed Nanoclusters .......................................... 100 5.3.2 CD19 Nanocluster Integrity Does Not Depend on Cortical Actin ... 100 5.3.3 The Tetraspanin CD81 Regulates CD19 Nanoclusters ..................... 101 5.3.4 CD19 Nanoclusters Coalesce with IgM in Areas of Signaling ........ 102
5.4 Compartmentalization Emerges as a Concept from Imaging Studies .......... 104 5.4.1 Compartmentalization of the Plasma Membrane by the Actin-
Based Membrane Skeleton ............................................................... 104 5.4.2 Regulation of BCR Mobility and B Cell Signaling through the
Actin Cytoskeleton ........................................................................... 104 5.4.3 BCR and CD19 Exist as Cytoskeleton-Independent Nanoclusters ... 105
Acknowledgment ................................................................................................... 106 References .............................................................................................................. 106
Immunity is the capability to detect, resist, and overcome a challenge that is posed by any foreign substance. This is carried out by a set of organs and tissues that are collectively referred to as the immune system. Its adaptive branch is able to respond to virtually any feature on a pathogen by the generation of highly specic receptors that recognize this so-called antigen-it adapts to the challenge and also ensures highly specic and long-lasting protection.1
