CD19 can regulate B lymphocyte signal transduction independent of complement activation.

Activation Transduction Independent of Complement CD19 Can Regulate B Lymphocyte Signal

CD19 and CD22 regulate a B lymphocyte signal transduction pathway that contributes to autoimmunity.

The fate of B lymphocytes is dependent on intrinsic and B cell antigen receptor (BCR)-induced signals. These signals are modified and interpreted by other cell-surface molecules such as CD19 and CD22 that govern mature B cell activation. This review assesses our current understanding of how CD19 and CD22 regulate B lymphocyte signaling and how alterations in these response-regulators contribute...

Complement component C3d-antigen complexes can either augment or inhibit B lymphocyte activation and humoral immunity in mice depending on the degree of CD21/CD19 complex engagement.

C3d can function as a molecular adjuvant by binding CD21 and thereby enhancing B cell activation and humoral immune responses. However, recent studies suggest both positive and negative roles for C3d and the CD19/CD21 signaling complex in regulating humoral immunity. To address whether signaling through the CD19/CD21 complex can negatively regulate B cell function when engaged by physiological ...

Qualitative Regulation of B Cell Antigen Receptor Signaling by CD19: Selective Requirement for PI3-Kinase Activation, Inositol-1,4,5-Trisphosphate Production and Ca2+ Mobilization

Genetic ablation of the B cell surface glycoprotein CD19 severely impairs the humoral immune response. This requirement is thought to reflect a critical role of CD19 in signal transduction that occurs upon antigen C3dg coligation of antigen receptors with CD19 containing type 2 complement receptors (CR2). Here we show that CD19 plays a key accessory role in B cell antigen receptor signaling ind...

CD19 amplifies B lymphocyte signal transduction by regulating Src-family protein tyrosine kinase activation.

Ligation of the B cell Ag receptor (BCR) induces cellular activation by stimulating Src-family protein tyrosine kinases (PTKs) to phosphorylate members of the BCR complex. Subsequently, Src-family PTKs, particularly Lyn, are proposed to phosphorylate and bind CD19, a cell-surface costimulatory molecule that regulates mature B cell activation. Herein, we show that B cells from CD19-deficient mic...