Immunoglobulin G deficiency

IgG deficiency (Immunoglobulin G deficiency): Description, Causes and Risk Factors:IgGIgG antibodies are the smallest but most abundant antibodies in the body, making up 75-80% of all the antibodies in the body. They are present in all body fluids. The IgG antibodies are considered the most important antibodies for fighting against bacterial and viral infections. They are the only antibodies that can cross the placenta. Therefore, the Immunoglobulin G deficiency antibodies of a pregnant woman help protect her fetus. IgG isotypes are associated with complement fixation (immune response in which an antigen-antibody combination deactivates a complement), opsonization (process by which antigens are altered so that they are more readily and more efficiently engulfed and destroyed by immune cells), fixation to macrophages, and membrane transport.Immunoglobulin G deficiency is the immunoglobulin molecule normally present in highest concentration in both intra- and extravascular spaces, with a mean normal adult serum concentration of 1200 mg/dL. It is of particular importance in secondary antibody responses (immunologic memory), and it subserves a major role in host defense against infection. Molecules of the IgG isotype are involved in complement fixation, opsonization and fixation to macrophages. It is the only class of immunoglobulin transported across the placenta from the mother to the fetus.Immunoglobulin G is essential to healthy immune system functioning. IgG helps neutralize bacteria, viruses, and environmental toxins before they can infect and damage body cells. An Immunoglobulin G deficiency deficiency can leave a person susceptible to chronic and recurring infections, especially respiratory infections such as bronchitis and pneumonia. Most patients who have the condition need to take antibiotics on a regular basis and schedule frequent checkups with their doctors to prevent serious complications. In the case of a severe IgG deficiency, periodic blood transfusions may be necessary to replenish IgG levels throughout the patient's life.Immunoglobulin G subclasses: The relative proportion of each of the IgG subclasses is generally constant within the total amount of IgG present in a given individual: IgG1 constitutes 60% to 65%, IgG2 20% to 25%, IgG3 5% to 10%, and IgG4 3% to 6% of total IgG. The mean normal adult serum concentration of IgG1 is 840 mg/dL, IgG2 is 240 mg/dL, IgG3 is 80 mg/dL, and of IgG4 is 40 mg/dL.IgG1 deficiency: Most patients have IgG1 deficiency also have low levels of other immunoglobulins. This condition is called common variable immunodeficiency (CVID).
  • IgG2 deficiency: IgG2 subclass deficiency, which occurs either as an isolated entity or in combination with IgG4 deficiency, is the most common subclass deficiency. Some patients with IgG2 deficiency may be asymptomatic, which may be because the antibody response was shifted to another Immunoglobulin G deficiency subclass. Children with IgG2 and IgG4 deficiency who also have systemic lupus erythematosus (chronic inflammatory connective tissue disease) may present experience cardiac tamponade (compression of the heart) rather than more common signs of systemic lupus erythematosus (like nephropathy and arthritis). This particular deficiency usually causes the highest frequency of infectious complications, especially in the respiratory tract (like bronchiectasis, bronchopneumonia, bronchitis, obstructive lung disease and asthma). This because the IgG2 antibodies play a vital role in the immune response to organisms with polysaccharide capsules (like H. influenzae type B). In addition, IgG2 deficient patients may be unable to produce specific antibodies after receiving certain vaccines, including the pneumococcal or the Haemophilus influenzae vaccines.
  • IgG3 deficiency: IgG3 deficiency, which may occur with IgG1 deficiency, has been associated with recurrent upper and lower respiratory tract infections. IgG3 may play an important role in the primary immune response to viral respiratory agents. Also, IgG3 is the predominant antibody response to the Moraxella catarrhalis bacteria, which is commonly found in patients who have chronic sinusitis.
  • IgG4 deficiency: IgG4 deficiency occurs in 10-15% of the general population. Researchers have described selective IgG4 deficiency in patients who have severe recurrent respiratory tract infections and bronchiectasis. When IgG deficiency occurs with low levels of both IgG4 and IgA, it is usually associated with ataxia-telangiectasia.
Several different factors can contribute to an IgG deficiency, but most cases are associated with inherited genetic disorders. X-linked agammaglobulinemia, a condition that primarily affects males, inhibits the development of IgG-creating B cells in the immune system. Genetic conditions tend to become prevalent in infancy or very early childhood. A person can also develop an IgG deficiency later in life due to protein malnutrition, kidney failure, or cancer. In addition, long-term use of anticonvulsants and immunosuppressive drugs for other conditions has been linked with diminished Immunoglobulin G deficiency levels.Symptoms:An IgG deficiency itself does not normally cause physical symptoms, but it can leave the body highly vulnerable to frequent viral and bacterial infections. A person with an IgG deficiency is likely to experience recurring respiratory infections that can cause bronchitis, pneumonia, and obstructive lung disease. Chronic sinus infections, influenza, and bacteria-related skin infections are also common with IgG deficiencies. Severely low levels of IgG can also render vaccines useless, and vaccinations may actually trigger the illnesses they are designed to prevent.Diagnosis:The standard diagnostic test for IgG subclass deficiency is an enzyme-linked immunosorbent assay (ELISA) or a radial immunodiffusion test. Test results may vary from one laboratory to another. A healthcare provider should also evaluate the patient's response to vaccines. Patients who have IgG2 subclass deficiency often have poor responses to the Pneumococcal vaccine.Enzyme-linked immunosorbent assay (ELISA): An enzyme-linked immunosorbent assay is a rapid test where an antibody or antigen is linked to an enzyme in order to detect a match between an antibody and antigen. If the target substance is present in the blood sample, the test solution will have an intense color reaction that is caused by the attached enzyme.
  • Radial immunodiffusion: A radial immunodiffusion test measures the amount of serum proteins in the blood.
Blood test: The amount of active binding antibodies in the blood can be determined by measuring the levels of antibodies to various vaccines (like diphtheria, tetanus, measles or pneumococci). Patients who have IgG2 subclass deficiency are often unable to produce specific antibodies after receiving the Pneumococcal vaccine.Treatment:Some patients do not need to receive treatment directly targeted at their deficiencies. If IgG levels are moderately low, daily antibiotics and regular visits to the doctor's office may be sufficient. IgG replacement therapy, which involves transfusions every three to four weeks, may be needed if levels are very low. Surgery is not effective at improving a deficiency, but a procedure may be needed if infections have seriously damaged lung or sinus tissue. Most patients are able to manage their conditions when they take preventive measures against infections and follow their doctors' orders.Gammaglobulin therapy: Gammaglobulin prophylaxis (preventative treatment) has been shown in some studies to reduce the number of infections and courses of antibiotics in patients who have substantial IgG subclass deficiencies. Dosages range from 200 to 400mg/kg, given once every three or four weeks.It is recommended that trough immunoglobulin levels be monitored regularly to help define the optimal time between doses since immunoglobulin clearance varies among individuals. Patients should maintain trough levels at 400-500mg/dL during therapy.Although the benefits of gammaglobulin therapy are significant, some patients may experience side effects. About 3-12% of patients who receive gammaglobulin therapy develop headache, myalgia (muscle pain), chills, fever and mild nausea upon infusion. If symptoms are intolerable, the infusion rate may be decreased to 0.01mL/kg/min to reduce side effects. In addition, side effects can also be minimized with antihistamines, acetaminophen and/or hydrocortisone.Immunizations: Vaccination is recommended in patients who do not have antibodies to Pneumococcus and Haemophilus polysaccharides, regardless of whether they have a IgG2 subclass deficiency. If the patient does not respond to Pneumococcus and Haemophilus polysaccharide vaccines, they may be revaccinated with protein-conjugated Pneumococcus and Haemophilus polysaccharide vaccines.Integrative Therapies:Massage: Preliminary evidence suggests massage therapy may preserve immune function. Further research is needed before a firm conclusion can be made.Meditation: Preliminary research reports increased antibody response after meditation. Further study is needed to confirm these findings.Other Supplements May Include:Zinc: Zinc appears to be an essential trace element for the immune system, but research on the effect of zinc supplementation on immune function is scant and mostly focuses on patients with specific diseases. Zinc gluconate appears to exert beneficial effects on immune cells, improving CD3 and CD4 counts and increasing CD4/CD8 ratios in children. There are relatively few studies that examine zinc levels and the effects of zinc supplementation on the health of the elderly population. Further research is needed before a recommendation can be made. Zinc is regarded as a relatively safe and generally well-tolerated therapy, when taken at recommended doses, and few studies report side effects. The recommended daily dose for adult and teenage males is 15mg. The recommended daily dose for adult and teenage females is 12mg. The recommended daily dose for pregnant females is 15mg and 16-19mg for breastfeeding females. The recommended daily dose for children ages 4-10 is 10mg, and 5-10mg for children 0-3 years old.
  • Arginine: Preliminary study results suggest that arginine supplementation may enhance the immune response elicited by the pneumococcal vaccine in older people. More studies are needed to confirm these results.
  • Astragalus: Astragalus has been suggested as an immune system stimulant in preliminary laboratory and animal research, and in traditional accounts. Reliable human studies are lacking. High-quality human research is necessary before a firm conclusion can be drawn.
  • Beta-carotene: Preliminary research of beta-carotene for immune system maintenance or stimulation shows mixed results. Further research is needed before a conclusion can be drawn.
  • Cat's claw: A few early studies suggest that cat's claw may boost the immune system. However, results from different studies are conflicting. Therefore, there is not enough information to recommend cat's claw for this use.
  • Copper: Copper is involved in the development of immune cells and immune function in the body. Severe copper deficiency appears to have adverse effects on immune function, although the exact mechanism is not clear.
  • Echinacea: Echinacea has been studied alone and in combination preparations for immune system stimulation. It remains unclear if there are clinically significant benefits. Additional studies are needed in this area before conclusions can be drawn regarding safety or effectiveness.
  • Gamma-linolenic acid (GLA): Few clinical trials have investigated the effect of GLA on immune responses in healthy human subjects. Results from one randomized, clinical trial suggest that GLA, as blackcurrant seed oil may offer some benefits. Further, well-designed clinical trials are required before definite conclusions can be made.
  • Ginseng: A small number of studies report that ginseng may stimulate activity of immune cells in the body, improve the effectiveness of antibiotics in people with acute bronchitis and enhance the body's response to influenza vaccines. Additional studies are necessary before a clear conclusion can be reached.
  • Goldenseal: Goldenseal has been suggested to be an immune system stimulant. However, there is little human or laboratory evidence in this area. More research is needed before a firm conclusion can be drawn.
  • Maitake mushroom: Animal and laboratory studies suggest that beta-glucan extracts from maitake may alter the immune system. However, no reliable studies in humans are available.
  • Mistletoe: A few small trials found mistletoe to be promising as an immunostimulant in individuals with the common cold. Further studies are needed to confirm these results.
  • Probiotics: Lactobacillus in fermented milk, low-fat milk or lactose-hydrolyzed low-fat milk may enhance immune function. Bifidobacterium may also enhance immune function. However, commercially produced yogurt may not yield similar benefits. There is some evidence that probiotics added during food preparation (e.g., waffles with Enterococcus faecium M-74 added) can enhance immune functioning. More studies are needed, particularly with yogurt, to give concrete recommendations.
  • Vitamin A (retinal): Vitamin A deficiency may compromise immunity, but there is no clear evidence that additional vitamin A supplementation is beneficial for immune function in patients who are not vitamin A deficient.
  • Vitamin B6 (pyridoxine): Vitamin B6 is important for immune system function in older individuals. One study found that the amount of vitamin B6 required to reverse immune system impairments in elderly people was more than the current recommended dietary allowance (RDA). Well-designed clinical trials on vitamin B6 supplementation for this indication are needed before a recommendation can be made.
  • Vitamin E: Studies of the effects of vitamin E supplementation on immune system function have yielded mixed results. Further research is needed before a clear conclusion can be drawn.
  • DHEA (dehydroepiandrosterone): Some textbooks and review articles have suggested that DHEA can stimulate the immune system. However, current scientific evidence does not support this claim.
  • Lycopene: It has been proposed that lycopene and other carotenoids, such as beta-carotene, may stimulate the immune system. However, several studies of lycopene supplements and tomato juice intake in humans report no effects on the immune system.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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