Immunoglobulin Deficiency: Symptoms & Treatment

Instructor: Amanda Robb

Amanda has taught high school science for over 10 years. They have a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. They also are certified in secondary special education, biology, and physics in Massachusetts.

In this lesson we'll learn the basics about immunoglobulins and how they function in the body. Then, we'll look at what happens when the body doesn't make enough of each type. We'll also cover treatment options for people with these deficiencies.

What Are Immunoglobulins?

When you're sick, a war rages inside your body. Bacteria and viruses, known as pathogens, battle in your throat and lungs for entry into your body. They want the nutrients and space that your body works hard to produce and maintain, but the tissues in your body aren't going down without a fight.

A large component of your immune system are the white blood cells ,which are the soldiers of your body, combating invading pathogens. There are different types of white blood cells in your body, but B-cells are the type that will be the focus of our lesson today. B-cells are white blood cells that make special proteins called immunoglobins, also known as antibodies, that attach to pathogens and alert the immune system. When B cells don't make enough of these antibodies the condition is known as an immunoglobulin deficiency.

B-cells make antibodies that attach to antigens on pathogens to destroy them during an infection
B-cell

Types of Immunoglobulin Deficiencies

The B-cells make different types of immunoglobulins depending on what the invader is. There are five main categories, immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin E (IgE), immunoglobulin M (IgM) and immunoglobulin D (IgD). Each immunoglobulin does a different job in the body, so there are different symptoms for each immunoglobulin deficiency, which is what we will cover next.

Structure of each class of immunoglobulins
classes of antibodies

IgA Deficiency

IgA is the main antibody used to protect the mucus coated surfaces in your body. Your intestines, lungs, reproductive and urinary tracts are all protected by mucus filled with IgA antibodies. It's an important front line for keeping pathogens that have access to these surfaces at bay. You can think of them as soldiers guarding the border.

People with IgA deficiency have trouble with respiratory infections such as bronchitis. Since IgA is located in the digestive system as well, these individuals suffer from irritable bowel syndrome and other intestinal infections. Anyone can get these infections, but people with an IgA deficiency tend to develop them more often.

The top panel shows a healthy lung and the bottom shows a lung infected with bronchitis which is common in patients with IgA deficiency
bronchitis

There is no treatment for people with IgA deficiency, although some do develop IgA antibodies gradually over their lifetime. You might be thinking, couldn't we just give them more IgA antibodies? The answer, unfortunately, is no. The immune systems of people without IgA think that any new IgA donated is an invader, and try to destroy it. When that happens, the body can go into shock. An example of this would be getting a blood transfusion from the wrong blood type. Since the body never had IgA, the IgA appears foreign and triggers a full immune response, just like a bacteria or virus would.

IgG deficiency

IgG is the most common antibody, and circulates our blood. Thus, people without IgG antibodies have a wide range of infections like ear, sinus, lung and throat infections. Like with IgA deficiency, any infection can be treated with antibiotics. Usually, there are no additional treatments needed after taking antibiotics, but if the symptoms become severe or the infections become resistant to antibiotics, IgG replacement therapy can be used.

Unlike IgA deficiency, IgG antibodies can be purified from a donor's blood and given to the patient through an IV, or an injection under the skin. The patient doesn't usually go into shock as they would with IgA antibodies, but may have mild symptoms such as headaches or muscle soreness.

IgE Deficiency

IgE is also found in mucus, and is involved in allergic reactions and getting rid of parasites. IgE deficiency has been studied less than other deficiencies like IgA and IgG, so there is less known about it. Some studies have found that having low IgE contributes to respiratory infections, and increased risk of autoimmune diseases, like in IgA deficiency. Usually patients complain of fatigue and respiratory infections. There is no way to replace IgE currently, so doctors usually treat the resulting illnesses as they would in a typical patient.

IgM Deficiency

IgM is the first antibody made during an infection. Think of it like an emergency first responder. IgM signals for more specific IgG antibodies to be made en masse, and activates the rest of the immune system.

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