Rare disease month, day 2: CVID (Common variable immunodeficiency)

Common variable immunodeficiency (CVID) is a primary disease of the immune system characterized by inability of B cells to generate an appropriate antibody response. CVID patients demonstrate low levels of serum IgG alongside other deficiency of IgM, IgA, or both. Diagnosis is based upon both serum immunoglobulin levels; decreased vaccine response; and exclusion of any other condition that could explain these inadequacies.

As the result of an inherent inability to properly defend against infection, CVID patients results in recurrent respiratory infections, both upper and lower. Specifically, encapsulated bacteria such as S. pneumoniae and K. pneumoniae are the most frequent pathogens. Atypical organisms like Mycoplasma spp. are known to cause infections in this population. Recurrent respiratory infection can cause chronic inflammation, leading to chronic sinusitis, hearing loss, bronchiectasis, and structural damage to the lungs.

CVID patients are at increased risk of complications beyond infections. Approximately 15% of patients develop cancer. 20-25% of patients report autoimmune disease. A significant amount of CVID patients with autoimmune disease have low blood counts as a result.

CVID can lead to known complications affecting the lymphatic system. 10-25% of CVID patients develop granulomatous lymphocytic interstitial lung disease. Enlarged lymph nodes occur in approximately 20% of CVID patients. Infiltration by lymphoid cells can be found in multiple organs, including kidney and liver.

Gastrointestinal manifestations are not unusual for CVID patients and can affect any portion of the tract. Inflammatory bowel disease is common. Of note, small bowel enteropathy is well documented in this population and may resemble inflammation seen in celiac disease. CVID patients may also demonstrate nodular lymphoid hyperplasia upon biopsy.

Treatment for CVID is based upon replacing the missing antibodies through administration of intravenous or subcutaneous gammaglobulin. While gammaglobulin replacement can help significantly with immune defense, CVID patients are still at risk for progression of organ damage. Specifically, obstructive or restrictive lung disease, along with bronchiectasis, may be stemmed by gammaglobulin replacement.

For more information, please visit the Immune Deficiency Foundation.

Reference:

Tam JS, Routes JM. (2013) Common variable immunodeficiency. Am J Rhinol Allergy, 27(4), 260-265.