CD21/CD35 in B cell activation

Semin Immunol. 1998 Aug;10(4):279-86. doi: 10.1006/smim.1998.0120.


The stimulus induced via the B cell receptor is a major factor in determination of the fate of naive B cells resulting in activation, elimination or anergy. The strength of B cell signal transduction is dependent not only on the affinity of antigen binding, but by positive signals via the co-receptor CD21/CD19/Tapa-1. Absence of CD21 expression by B cells results in an impaired humoral response to T-dependent antigens which is characterized by a reduction in B cell follicular retention and germinal center survival. The ligand for CD21 is complement C3d which becomes attached to antigen on activation of the complement system. Thus, the complement system of innate immunity is an important regulator of B lymphocytes.

Publication types

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

MeSH terms

  • B-Lymphocytes / cytology
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / metabolism
  • Complement C3d / metabolism
  • Germinal Center / cytology
  • Humans
  • Immunity
  • Lymphocyte Activation*
  • Receptors, Antigen, B-Cell / metabolism
  • Receptors, Complement 3b / genetics
  • Receptors, Complement 3b / metabolism*
  • Receptors, Complement 3d / genetics
  • Receptors, Complement 3d / metabolism*
  • Signal Transduction


  • Receptors, Antigen, B-Cell
  • Receptors, Complement 3b
  • Receptors, Complement 3d
  • Complement C3d