In the context of multiple myeloma, IgD refers to immunoglobulin D, one of the five main classes of antibodies produced by plasma cells (the others are IgG, IgA, IgM, and IgE).
IgD myeloma is a relatively rare subtype of multiple myeloma, accounting for about 1–2% of cases. In this form, the malignant plasma cells produce excessive amounts of IgD antibody.
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