Class switch regulation

As compared to DCs, B cells are very poor APCs and play a major role as source for antibodies. Upon stimulation by antigens and in the presence of T cells at the border of the T-cell-B-cell area, adjacent to follicles, B cells become antibody-secreting cells and eventually form a germinal center (GC) response. GCs are specialized follicles for B-cell expansion, somatic hypermutation, and class switch recombination, processes that are regulated by T cells, follicular DCs, and other cells. In this process of B-cell maturation, Tregs seem to play a critical role, as in several immune diseases, which are characterized by aberrant antibody... 

The enzymes responsible for class switching have not been identified but it is known that they are not products of the RAG genes. There is considerable information on the regulation of the class specificity of the switch (reviewed by Stavnezer,... 

CSR Cluster-situated regulator class-switch recombination... 

Peng SL, Szabo SJ, Glimcher LH. T-bet regulates IgG class switching and pathogenic autoantibody production. Proc Natl Acad Sci USA. 2002 99 5545-5550. 

Bottaro, A., Lansford, R., Xu, L., Zhang, J., Rothman, P., and Alt, F. (1994). S region transcription per se promotes basal IgE class switch recombination but additional factors regulate the efficiency of the process. EMBO J. 13, 665-674. 

McBride KM, Gazumyan A, Woo EM, Schwickert TA, Chait BT, Nussenzweig NC. Regulation of class switch recombination and somatic mutation by AID phosphorylation. J Exp Med. 2008 205 2585-94. 

Kawamata T, Lu J, Sato T, Tanaka M, Nagaoka H, Agata Y, Yoyoshima T, Yokoyama K, Oyaizu N, Nakamura N, Ando K, Tojo A, Kotani A. Imatinib mesylate directly impairs class switch recombination through down-regulation of AID its potential efficacy as an AID suppressor. Blood. 2012 119 3123-7. 

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