« Understanding Primary Immunodeficiency (PI)

Types of PI

Primary immunodeficiency (PI) diseases are characterized in many different ways, including:

  • Low antibody levels
  • Defects in antibodies
  • Defects in the cells and proteins of the immune system (for example, T cells, B cells, neutrophils, or the complement system)

These defects make people susceptible to recurrent infections, and other complications that may require different therapies. The most common primary immunodeficiency types result in an inability to make a very important type of protein called antibodies or immunoglobulins, which help the body fight off infections from bacteria or viruses. In addition to increased susceptibility to infection, people with PI may also have autoimmune diseases in which the immune system attacks their own cells or tissues.

PI Type:

Common Variable Immune Deficiency (CVID)

Definition of CVID

People with CVID have decreased levels of antibodies (immunoglobulins) in the blood and are therefore more likely to get infections. Antibody levels may be low (hypogammaglobulinemia) or absent (agammaglobulinemia). These individuals may have normal numbers of the cells that produce antibodies (B lymphocytes), but these cells do not function properly.

Common Variable Immune Deficiency Symptoms Common Variable Immune Deficiency Symptoms

The name CVID reveals information about the condition:

Common: CVID is a relatively common type of PI found in about 1 in 25,000 persons.

Many aspects of CVID differ from person to person including the levels of antibodies in the blood and type of antibody that is decreased, the severity of signs and symptoms, and the time of life — childhood, adolescence, or adulthood — during which symptoms arise.

Because CVID may be diagnosed later than other types of PI, some other names that have been used for it are acquired agammaglobulinemia, adult onset agammaglobulinemia, or late onset hypogammaglobulinemia.

Though the exact cause of this disorder is unknown, recent studies have shown that a small group of genes appears to be involved for some people with the disorder.

Symptoms of CVID

Some people with CVID have symptoms as young children, while many others may not develop symptoms until their 20s or 30s—or even later. The most common symptoms are recurring infections involving the ears, sinuses, nose, bronchi (breathing tubes), and lungs (respiratory tract). Severe, repeated infections of the lungs can result in permanent widening and scarring of the bronchi—a chronic condition called bronchiectasis.

People with CVID may also develop enlarged lymph nodes in the neck, chest, or abdomen. The spleen, an organ related to the immune system, may also become enlarged. Lymphocytes may collect in groups inside the intestine known as Peyer’s patches.

Painful swelling of the joints, a condition called polyarthritis, can also develop in people with CVID. The larger joints—knees, ankles, elbows, and wrists—are affected most often.

Gastrointestinal complaints such as abdominal pain, bloating, nausea, vomiting, diarrhea, and weight loss can occur in people with CVID.

People with CVID may have a greater risk of cancer, especially cancers of the lymphoid system and gastrointestinal tract.

Common Variable Immune Deficiency Diagnosis Common Variable Immune Deficiency Diagnosis

Diagnosis of CVID

Doctors suspect CVID when a child or adult has a history of recurrent infections of the ears, sinuses, bronchi, and lungs. The diagnosis is made when a blood test shows low levels of antibodies in the blood, including IgG, IgA, and sometimes IgM. Special lab tests can tell whether B lymphocytes and T lymphocytes are working properly. Another part of the diagnosis of CVID is done by measuring antibody levels in the blood against vaccines such as tetanus, diphtheria, and pneumococcal polysaccharide.

Treating CVID

Only your doctor can determine which treatment is right for you and your specific health needs. Visit our Treating PI section to read about the types of PI treatment and download questions to ask your doctor.