T cell-dependent B cell activation

Annu Rev Immunol. 1993;11:331-60. doi: 10.1146/annurev.iy.11.040193.001555.


B cells obtain help from T cells in the antibody response by acting as antigen-specific antigen presenting cells. A direct signal through binding of antigen to membrane Ig can enhance B cell antigen presentation and T-dependent B cell activation, but is not required for a productive interaction between a small resting B cell and a differentiated helper T cell. As a result of helper T cell recognition of antigen on the B cell surface, the T cell becomes activated and in turn activates the B cell. T cell help has two components: lymphokines which act as growth and differentiation factors for B cells, and additional signals which require cell contact and enable B cells to respond to lymphokines. Contact help activity is regulated like lymphokine synthesis and secretion. Because contact help activity is retained by fixed, activated helper T cells and plasma membranes prepared from activated T cells, contact help is likely to be owing to new proteins expressed as membrane-bound lymphokines or activation antigens on helper T cells. Once induced, contact help can be delivered to B cells independently of recognition of antigen/class II MHC. A newly identified activation antigen of helper T cells, a ligand for the B cell differentiation antigen, CD40, is a key component of contact help. The roles of other T and B cell membrane molecules in contact help are reviewed.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Antibody Formation
  • Antigen-Presenting Cells / immunology
  • B-Lymphocytes / immunology*
  • Cell Adhesion / immunology
  • Cytokines / immunology
  • Histocompatibility Antigens
  • Humans
  • Lymphocyte Activation
  • Lymphocyte Cooperation
  • Receptors, Antigen, B-Cell
  • Signal Transduction / immunology
  • T-Lymphocytes / immunology*


  • Cytokines
  • Histocompatibility Antigens
  • Receptors, Antigen, B-Cell