Immunoglobulins: Types (IgG, IgA, IgM, IgD, IgE)
Start with the big picture
All immunoglobulins share a basic structure of two heavy and two light chains. The heavy chain defines the class; the Fab region binds antigen, and the Fc region mediates effector functions. IgG is the main serum class and crosses the placenta; IgA is prominent in mucosal secretions; and IgM is the first antibody in a primary response and a strong complement activator. IgD is associated with naïve B cells, while IgE participates in allergic responses and defense against helminths. The lesson also compares class-switch signals, complement activity, and serum half-life, then relates these patterns to clinical examples such as selective IgA deficiency, elevated IgE, and an IgG spike in multiple myeloma.
What you'll learn
- Describe the shared structure of immunoglobulins and distinguish Fab from Fc functions.
- Compare the structures, locations, and key roles of IgG, IgA, IgM, IgD, and IgE.
- Relate CD40–CD40L and cytokine signals to IgA and IgE class switching.
- Compare immunoglobulin classes by complement activation and serum half-life.
- Recognize clinical associations involving IgG, IgA, and IgE.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
