Powered by pairing: the surrogate light chain amplifies immunoglobulin heavy chain signaling and pre-selects the antibody repertoire.
Selective expansion of functional pre-B cells is accomplished by the assembly of a signaling-competent pre-B cell receptor (pre-BCR) consisting of immunoglobulin mu heavy chains (muHC), surrogate light chains (SLC) and Igalpha/Igbeta. Here, we review recent data showing that muHCs, in the absence of SLC, deliver autonomous differentiation signals. However, enhanced signaling necessary for pre-B cell expansion requires cross-linking of pre-BCRs via the non-immunoglobulin tail of SLC's subunit lambda5. We also discuss how SLC's ability to modulate the strength of pre-BCR signals is controlled by a muHC's idiotype and its affinity to the chaperone BiP. In this model, BiP in concert with SLC functions as a pre-selector of the antibody repertoire.
Vettermann
Christian
C
Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, D-91054 Erlangen, Germany.
Herrmann
Kai
K
Jäck
Hans-Martin
HM
D000818:Animals; D015322:Gene Rearrangement, B-Lymphocyte / Q000276:immunology*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000502:physiology*; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007136:Immunoglobulins / Q000096:biosynthesis* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology*
D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007136:Immunoglobulins; D008562:Membrane Glycoproteins