Immunoglobulin D

IgD starts to be expressed when the B cell exits the bone marrow to populate peripheral lymphoid tissues.

This is consistent with the reduction in the number of peripheral B cells, reduced serum IgE level and defective primary IgG1 response in IgD knockout mice.

C-terminal regions are rich in lysine, glutamate and arginine residues modified with O-glycosylation for binding a putative IgD receptor on the surface of activated T cells.

[11][12] Human IgD with its H region interacts with heparin and heparan sulphate proteglycans expressed in the basophils and mast cells.

In the human heavy chain locus, 3' of the V-D-J cassette is a series of C (for constant) genes, each conferring an Ig isotype.

Zinc finger protein 318 (ZNF318) has a role in the promotion of IgD expression and controlling the alternative splicing of the long pre-mRNA.

[6][17] Counter-intuitive to the contemporary dogmas that suggest these activated immune responses via IgD expression can potentiate autoimmune diseases and allergic inflammation, a 2010 study by Nguyen TG et al. has first demonstrated that treatments with a B-cell activating monoclonal anti-IgD antibody can attenuate disease severity in an animal model of collagen-induced arthritis.

[15] This novel therapeutic effect by anti-IgD antibody treatment was later confirmed in mouse models of epidermolysis bullosa acquisita[18] and in chronic contact hypersensitivity.

[19] Studies have shown that levels of secreted lgD are usually elevated in patients with an autoimmune disease, and recently it has been demonstrated that IgD enhanced the activation of peripheral blood mononuclear cells in Rheumatoid Arthritis (RA) patients leading to the hypothesis that IgD could be an immunotherapeutic target for the management of RA.