American Board of Internal Medicine (ABIM) Certification Practice Exam

Common variable immunodeficiency (CVID) is characterized by which of the following?

1. Increased levels of immunoglobulins

2. Normal immune function with recurrent infections

3. B- and T-cell abnormalities with hypogammaglobulinemia

4. Overproduction of antibodies

The correct answer is: B- and T-cell abnormalities with hypogammaglobulinemia

Common variable immunodeficiency (CVID) is characterized by B- and T-cell abnormalities, which contribute to its hallmark of hypogammaglobulinemia, or low levels of immunoglobulins in the blood. In patients with CVID, the B cells fail to function adequately, leading to a decreased ability to produce antibodies in response to infections. This condition is also associated with dysregulation of T cells, further compromising the immune response. The resulting immunodeficiency leaves individuals susceptible to recurrent infections, particularly those caused by encapsulated bacteria and certain viruses. Unlike conditions with normal immune function, patients with CVID experience significant clinical challenges due to the combined deficiencies in both humoral and cellular immunity. The absence of adequate immunoglobulin levels means these patients cannot rely on normal immune responses to protect them from common pathogens, hence the increased incidence of infections. Recognizing the immunological abnormalities in CVID is crucial for effective management and treatment strategies, including immunoglobulin replacement therapy.