Description: The human IgG4 ELISA is an enzyme-linked immunosorbent assay for the quantitative detection of human IgG4. The human IgG4 ELISA is for research use only. Not for diagnostic or therapeutic procedures.
IgG is the major immunoglobulin in blood, lymph fluid, cerebrospinal fluid, and peritoneal fluid and a key player in the humoral immune response. Serum IgG in healthy humans presents approximately 15% of total protein beside albumins, enzymes, other globulins and many more.
The Fc portion of IgG, but not F(ab')2 or Fab fragments, can cross the placenta of a mother to enter the fetal circulation providing the fetus with postpartum protection.
IgG molecules are able to react with Fc-gamma receptors that are present on the surfaces of macrophages, neutrophils, natural killer cells, and can activate the complement system.
The binding of the Fc portion of IgG to the receptor present on a phagocyte is a critical step in the opsonizing property IgG provides to the immune response. Phagocytosis of particles coated with IgG antibodies is a vital mechanism to cope with microorganisms.
IgG is produced in a delayed response to an infection and can be retained in the body for a long time. The longevity in serum makes IgG most useful for passive immunization by transfer of this antibody. Detection of IgG usually indicates a prior infection or vaccination.
Comprising usually less than 4% of total IgG, IgG4 does not bind to polysaccharides. Testing for IgG4 has been associated with food allergies in the past and recent studies have shown that elevated serum levels of IgG4 are found in patients suffering from sclerosing pancreatitis, cholangitis and interstitial pneumonia caused by infiltrating IgG4 positive plasma cells. The precise role of IgG4 is still mostly unknown.