American Board of Internal Medicine (ABIM) Certification Practice Exam

IgG4-related disease is characterized by infiltration of organs with what type of cells?

1. Neutrophils

2. IgG4-positive plasma cells

3. T-lymphocytes

4. B-lymphocytes

The correct answer is: IgG4-positive plasma cells

IgG4-related disease is specifically characterized by the infiltration of affected organs by IgG4-positive plasma cells. This condition often leads to specific types of organ involvement, such as the pancreas (leading to autoimmune pancreatitis), salivary glands, kidneys, and lymph nodes. The presence of these IgG4-positive plasma cells is a hallmark of the disease and can often be identified through immunohistochemistry in tissue samples. While other immune cells, such as T-lymphocytes and B-lymphocytes, may also be present in the inflammatory infiltrate, it is primarily the IgG4-positive plasma cells that define the histopathological findings associated with this disease. Their presence indicates an immune response typical of IgG4-related pathology, distinguishing it from other types of autoimmune or inflammatory diseases.