American Board of Internal Medicine (ABIM) Certification Practice Exam

What role do plasma cells play in the context of IgG4-related disease?

1. Regulatory effects on T cells

2. Production of IgG4 antibodies

3. Inhibition of inflammation

4. Stimulation of fibroblasts

The correct answer is: Production of IgG4 antibodies

Plasma cells are specialized B cells primarily responsible for the production of antibodies in response to antigens. In the context of IgG4-related disease, which is characterized by the accumulation of IgG4 plasma cells and elevated serum IgG4 levels, the primary function of these plasma cells is to produce IgG4 antibodies. The presence of IgG4 antibodies is a hallmark of this disease and plays a significant role in its pathology. IgG4-related disease often presents with various symptoms due to the immunological responses elicited by these antibodies. The production of IgG4 can lead to specific tissue responses, including fibrosis and the formation of masses or lesions in affected organs. Importantly, IgG4 is known for its unique properties among immunoglobulins; it generally does not activate complement and is associated with a less inflammatory response compared to other immunoglobulin subclasses. Thus, the role of plasma cells in this disease is fundamentally centered around their function as producers of IgG4 antibodies, which are integral to understanding the underlying mechanisms of IgG4-related pathology. In contrast, the other options do not accurately reflect the primary role of plasma cells in this disease. While regulatory effects on T cells and stimulation of fibroblasts may be related