Positive and negative selection events during B lymphopoiesis.

摘要: Early in B-cell development, large numbers of cells have to be generated, each which expresses only one type receptor (i.e. Ig) on its surface. This is achieved by the surface expression a pre-B cell containing μ heavy chains/surrogate light chain differentially provides signals for two responses precursor B at this stage development. On hand, it inhibition further rearrangements variable diverse-joining loci achieve allelic exclusion heavy-chain locus. other proliferative expansion factors between 20 and 100. Later tolerance autoantigens must established maintained. Tolerance developmental arrest induction secondary light-chain gene those IgM+ immature that are reactive presented primary generating organs. Even later when mature (s)IgM+/sID+ encounter them periphery, either deletion or anergy autoantigen-reactive occurs. Anergic sIg-dependent, slg-proximal defect signaling short-lived. Anergy can broken vitro polyclonal activation via ligation CD40 presence IL-4. A small part remaining not selected become mature, antigen-reactive slgM+/slgD+ cells. Molecules might guide such positive selection still remain identified.