What is CD40 on B cells?
CD40 is an important costimulatory molecule for B cells as well as dendritic cells, monocytes, and other APCs. The ligand for CD40, CD154, is expressed on activated T cells, NK cells, mast cells, basophils, and even activated B cells.
What happens to autoreactive B cells?
The presence of autoreactive B-cell receptors (BCRs) is potentially dangerous to the host since the activation of B cells with autoreactive BCRs can trigger the secretion of autoreactive antibodies (Abs) that cause autoimmune diseases.
Is CD40 constitutively expressed on B cells?
In addition to the noncanonical NF-κB pathway, the MAPKs Erk and Jnk were constitutively phosphorylated in unstimulated LMP1/CD40-expressing B cells. Our results provide direct evidence that constitutive CD40 signaling leads to the selective activation of the noncanonical NF-κB pathway and the MAPKs Jnk and Erk.
What is the role of CD40?
CD40L mediates a range of activities on B cells, including induction of activation-associated surface antigen, entry into cell cycle, isotype switching, Ig secretion, and memory generation. CD40–CD40L interaction also plays important roles in monocyte activation and DC maturation.
What cell expresses CD40?
dendritic cells
The expression of CD40 is diverse. CD40 is constitutively expressed by antigen presenting cells, including dendritic cells, B cells and macrophages. It can also be expressed by endothelial cells, smooth muscle cells, fibroblasts and epithelial cells.
What happens when CD40 is stimulated?
These results could be interpreted in three ways: long-term CD40 stimulation allows the expansion and differentiation of both memory and naive cells with or without isotype switching or no expansion of memory cells but expansion, differentiation, and isotype switching by naive cells.
How do autoreactive B cells become activated?
Autoreactive B cells bind DNA/RNA-containing complexes from dying cells or immune complexes (ICs), consisting of IgG bound to nuclear antigens and become activated though dual engagement of their surface B-cell receptor (BCR) and nucleic-acid sensing Toll-like receptors TLR7 and TLR9.
How are autoreactive B cells eliminated?
These findings suggest that autoreactive B cells exist unless they are harmful, but once harmful or dangerous events such as tissue destruction are sensed, the mature autoreactive B cells in the periphery are eliminated via a Fas-mediated process in a CD4(+) T cell-dependent manner.
How is CD40 activated?
In the macrophage, the primary signal for activation is IFN-γ from Th1 type CD4 T cells. The secondary signal is CD40L (CD154) on the Th1 cell which binds CD40 on the macrophage cell surface. As a result, the macrophage expresses more CD40 and TNF receptors on its surface which helps increase the level of activation.
What are CD40 immune cells?
CD40 is known to be expressed on additional hematopoietic cells, such as monocytes and dendritic cells (DCs) where it promotes cell survival and cytokine production [10] and can also signal to induce activation, proliferation and cytokine production from CD40L expressing CD4+ T cells [11].
Is CD40 expressed on T cells?
The ligand for CD40, CD154, is expressed on activated T cells and allows for interactions with APC during the cognitive phase of the immune response, as well as directing effector T cell-dependent B cell ac- tivation (3). The role of CD40 as a direct signal receptor has now been ex- panded to T cells.
What is CD40 microbiology?
Cluster of differentiation 40, CD40 is a costimulatory protein found on antigen-presenting cells and is required for their activation. The binding of CD154 (CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of downstream effects.