IgD has a primary role as which of the following?

IgD has a primary role as which of the following?

• A. Part of the B Cell Receptor
• B. Activates Basophils and Mast Cells
• C. Crosses Placenta
• D. Found in Mucosal Secretions

Answer: (A)

IgD’s primary function is as a membrane-bound immunoglobulin that forms the B cell receptor on naive B cells, pairing with IgM to recognize antigen and initiate signaling through the BCR complex to activate the B cell. This binding triggers the downstream signals (via Igα/Igβ) that lead to B cell proliferation and eventual antibody production. It is not the major antibody in mucosal secretions (that role belongs to IgA, with IgM also present) and it does not cross the placenta (that’s IgG). Activation of basophils and mast cells is most closely associated with IgE. So the best description is that IgD primarily serves as part of the B cell receptor on naive B cells, enabling antigen recognition and B cell activation.

IgD’s primary function is as a membrane-bound immunoglobulin that forms the B cell receptor on naive B cells, pairing with IgM to recognize antigen and initiate signaling through the BCR complex to activate the B cell. This binding triggers the downstream signals (via Igα/Igβ) that lead to B cell proliferation and eventual antibody production. It is not the major antibody in mucosal secretions (that role belongs to IgA, with IgM also present) and it does not cross the placenta (that’s IgG). Activation of basophils and mast cells is most closely associated with IgE. So the best description is that IgD primarily serves as part of the B cell receptor on naive B cells, enabling antigen recognition and B cell activation.