Helper T cells: delivery of cell contact and lymphokine-dependent signals to B cells.
In the effector phase of delivering T cell help for B cell differentiation, proteins induced following helper T cell activation deliver cell contact signals to the B cell that drive its activation and proliferation. Activation induced soluble lymphokines also deliver signals that, in conjunction with the contact signals, drive B cell differentiation and immunoglobulin class switching. Helper T cell activation leads to transient expression of a ligand for the constitutively expressed B cell surface protein, CD40. The CD40 ligand is involved in delivering the T cell induced contact signals. Regulation of synthesis of the CD40 ligand by activated helper T cells contributes to the maintenance of specificity of the antibody response. Knowledge of the molecules involved in delivering T cell help allows a clearer understanding of events regulating antibody affinity maturation, selection and class switching in vivo.
Kehry
M R
MR
Department of Immunology, Boehringer Ingelheim Pharmaceuticals, Inc, Ridgefield, CT 06877.
Hodgkin
P D
PD
D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000502:physiology; D001402:B-Lymphocytes / Q000276:immunology*; D019013:CD40 Antigens; D023201:CD40 Ligand; D002450:Cell Communication / Q000276:immunology*; D006801:Humans; D008222:Lymphokines; D008562:Membrane Glycoproteins / Q000502:physiology; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; D008222:Lymphokines; D008562:Membrane Glycoproteins; D023201:CD40 Ligand