American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the common manifestation associated with Common Variable Immunodeficiency?

1. Hypergammaglobulinemia

2. Hypogammaglobulinemia

3. Increased T-cell activity

4. Normal B-cell function

The correct answer is: Hypogammaglobulinemia

Common Variable Immunodeficiency (CVID) is characterized primarily by hypogammaglobulinemia, which refers to low levels of immunoglobulins or antibodies in the blood. This deficiency leads to a reduced ability to mount effective immune responses against infections, making individuals with CVID more susceptible to recurrent infections, particularly from encapsulated organisms. In CVID, there is a failure of B-cell differentiation into plasma cells, which are responsible for producing antibodies. As a result, patients exhibit insufficient levels of immunoglobulins (IgG, IgA, and IgM) despite having normal or even increased numbers of B-cells. This condition is crucial for understanding the immunological landscape of CVID, as it emphasizes the dysfunction in antibody production rather than the presence of antibodies. The other options describe conditions that do not align with the primary immunological defect associated with CVID. For instance, hypergammaglobulinemia, increased T-cell activity, and normal B-cell function would not be consistent with the hallmark features of CVID. Therefore, recognizing hypogammaglobulinemia as the correct manifestation is essential for diagnosing and managing this immunodeficiency effectively.