A 35 Year Old Man With Recurrent Infections

A 35-year-old male is seen by you in the hospital setting, after being admitted for pneumonia. Blood
cultures reveal Streptococcus pneumoniae. The patient was well until age 25 when he began having recurrent infections and developed an autoimmune hemolytic anemia. He also relates frequent sinus infections (real ones . . . not the kind we so often see) requiring antibiotics 8–10 times a year. His last bout of pneumonia required a stay in the ICU. You suspect immune deficiency in this individual.
What is the most useful test in making the diagnosis in this patient?

A) Complement levels.
B) Immunoglobulin levels.
C) CBC and differential.
D) Bone marrow biopsy.
E) Nitroblue tetrazolium test

Answer And Discussion:


The correct answer is “B.” Immunoglobulin levels.

The clinical picture for this patient is most consistent with Common variable immunodeficiency (CVID). CVID, or acquired agammaglobulinemia, is similar to Xlinked agammaglobulinemia, but generally has a later age of onset. In addition, it is associated with various gastrointestinal disorders, autoimmune disorders, and malignancy. Immunoglobulin levels are decreased secondary to inadequate B cell differentiation. Therefore, the most useful laboratory for diagnosis of  Common variable immunodeficiency  would be serum immunoglobulin levels.
With regard to the other options and other tests you might do to evaluate otherwise unexplained immunodeficiency:

• Complement levels will be low in patients with immunodeficiency secondary to complement disorders.
•  Nitroblue tetrazolium test will be abnormal in patients with phagocytic disorders.
• Response to vaccines will be muted or absent in humoral immunodeficiency (e.g., immunoglobulin deficiency).
• Delayed hypersensitivity skin testing (e.g., candida and mumps) may indicate a T-cell defect.

Treatment: The treatment of choice for CVID includes replacement IVIG, especially in this patient who has a history of life-threatening infections.

Prophylactic antibiotics may be required in addition to IVIG in some patients. 

Gene therapy is not currently possible because the genetic defect has not been identified. Although bone marrow transplantation is useful in other immune-deficient states, it is not indicated in CVID.