CD40 ligation in B cell activation, isotype switching and memory development.
Interaction of CD40 on B cells with its ligand on activated T helper cells is crucial for the generation of mature T-dependent antibody responses. Experimental observations suggest that CD40 ligation acts at several points in B cell differentiation; however, it is not clear whether the consequences of ligation are direct or indirect. While its role in B cell activation is clearly direct we discuss the several ways in which it might drive isotype switching, the influence that it has on the development of memory B cells and the possibility that certain types of T-dependent antibody response are CD40L-independent. Experiments in which the ligation of CD40 is blocked in vivo reveal that early CD40 signals are important for the development of memory B cells but this may only reflect the ability of 'memory precursors' generated by CD40 ligation to accept subsequent programming or survival signals.
Gray
D
D
Department of Immunology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Siepmann
K
K
Wohlleben
G
G
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D019013:CD40 Antigens; D023201:CD40 Ligand; D006801:Humans; D017578:Immunoglobulin Class Switching / Q000276:immunology*; D007156:Immunologic Memory / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008211:Lymphocyte Cooperation; D008562:Membrane Glycoproteins / Q000378:metabolism*
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; D008562:Membrane Glycoproteins; D023201:CD40 Ligand