CD19, CD21, and CD22: multifaceted response regulators of B lymphocyte signal transduction

Int Rev Immunol. 2001;20(6):739-62. doi: 10.3109/08830180109045588.


B lymphocyte development and function depend upon the activity of intrinsic and B cell antigen receptor (BCR)-induced signals. These signals are interpreted, amplified, fine-tuned, or suppressed through the precise actions of specialized cell surface coreceptors, or "response regulators," that inform B cells of their extracellular environment. Important cell surface response regulators include the CD19/CD21 complex, CD22, and CD72. CD19 establishes a novel Src-family protein tyrosine kinase (PTK) amplification loop that regulates basal signaling thresholds and intensifies Src-family PTK activation following BCR ligation. In turn, CD22 limits the intensity of CD19-dependent, BCR-generated signals through the recruitment of potent phosphotyrosine and phosphoinositide phosphatases. Herein we discuss our current understanding of how CD19/CD21 and CD22 govern the emergence and intensity of BCR-mediated signals, and how alterations in these tightly controlled regulatory activities contribute to autoimmunity in mice and humans.

Publication types

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

MeSH terms

  • Animals
  • Antigens, CD / chemistry
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • Antigens, CD19 / chemistry
  • Antigens, CD19 / genetics
  • Antigens, CD19 / metabolism*
  • Antigens, Differentiation, B-Lymphocyte / chemistry
  • Antigens, Differentiation, B-Lymphocyte / genetics
  • Antigens, Differentiation, B-Lymphocyte / metabolism*
  • Autoimmunity
  • B-Lymphocytes / immunology*
  • Cell Adhesion Molecules*
  • Humans
  • Lectins*
  • Lymphocyte Activation
  • Mice
  • Mice, Knockout
  • Models, Immunological
  • Receptors, Antigen, B-Cell / metabolism
  • Receptors, Complement 3d / chemistry
  • Receptors, Complement 3d / genetics
  • Receptors, Complement 3d / metabolism*
  • Sialic Acid Binding Ig-like Lectin 2
  • Signal Transduction
  • src-Family Kinases / metabolism


  • Antigens, CD
  • Antigens, CD19
  • Antigens, Differentiation, B-Lymphocyte
  • CD22 protein, human
  • Cd22 protein, mouse
  • Cell Adhesion Molecules
  • Lectins
  • Receptors, Antigen, B-Cell
  • Receptors, Complement 3d
  • Sialic Acid Binding Ig-like Lectin 2
  • src-Family Kinases