CD40 is a co-stimulatory receptor on B cells that, when bound to CD40 ligand (CD40L), sends a signal to the B-cell receptor. When there is a defect in CD40, this leads to defective T-cell interaction with B cells. Consequently, humoral immune response is affected. Certain insults, usually from encapsulated bacteria and toxin, then have a greater opportunity to damage the body.
Hyper IgM syndrome
Hyper-IgM syndrome type 5
Hyper-IgM syndrome type 2
Hyper-IgM syndrome type 3
Hyper-IgM syndrome type 4
Hyper-IgM syndrome type 1
Anti-IgLON5 disease
Common variable immunodeficiency