CD40, a costimulatory protein member of the TNFR superfamily, has been identified to regulate a broad range of cellular responses, including proliferation, differentiation, and cell death. CD40 can be found on several cell types, such as B cells, macrophages, dendritic cells, and fibroblasts, demonstrating its critical role in immune response and host defense. The binding of CD40L to CD40 stimulates APCs and leads to a number of downstream effects. Different gene expression patterns are activated by CD40 for certain cell types. In addition, several pathways are triggered through CD40 signal transduction. Examples include the NF-κB, MAPK, Jak3/STAT3, and PI3K/Akt pathways.
Mutations in CD40L for humans interfere with the B cells’ ability to perform Ig class switching, bring about abnormal antibody levels, and impair the ability to fight bacterial infections. Research has also pointed out their association with Hyper IgM syndrome (HIGM1). Furthermore, CD40 mutations are linked with autoimmune inflammatory diseases like multiple sclerosis and rheumatoid arthritis.
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