Overview and Clinical Significance

Immunoglobulin D (IgD) is a less abundant antibody primarily found on the surface of immature B cells, playing a role in immune regulation and mucosal defense. Despite its low serum concentration, IgD has unique immunological functions.

Clinical Significance

• B Cell Activation & Immune Modulation: IgD helps regulate B cell maturation and antigen recognition, influencing immune responses.
• Respiratory & Mucosal Immunity: Secretory IgD is involved in mucosal defense, particularly in the upper respiratory tract.
• Autoimmune & Inflammatory Disorders: Elevated IgD levels may be linked to chronic inflammation, periodic fever syndromes, and autoimmune conditions.
• Monoclonal Gammopathies & Plasma Cell Disorders: IgD myeloma is a rare but aggressive form of multiple myeloma, often associated with renal impairment and amyloidosis.
• Hyperimmunoglobulinemia D Syndrome (HIDS): This rare autoinflammatory disorder is characterized by recurrent fever episodes and elevated IgD levels.

IgD remains an enigmatic immunoglobulin, influencing B cell function, mucosal immunity, and disease pathology.

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