Description: 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.
