Nonenzymatic glycation of immunoglobulins leads to an impairment of immunoreactivity.
Incubation of purified human and rabbit immunoglobulin G with glucose leads to covalent incorporation of the sugar into the protein, depending on glucose concentration, incubation time and pH. Furthermore, the level of glycated immunoglobulin G from normal and diabetic subjects has been determined using the thiobarbituric acid reaction. The median for glycated immunoglobulin G, expressed as mmol 5-hydroxymethylfurfural per mol IgG, obtained from 20 normal and 29 diabetic subjects was 62 and 107, respectively. Glucose incubation of immunoglobulin G purified from rabbit anti-human-transferrin serum, from human anti-varicella/zoster virus serum and from human anti-lues-spirochete serum, respectively, leads to a marked decrease in biological activity, as determined in a micro complement fixation test. Inactivation of specific antibody was dependent on incubation time and glucose concentration employed. Loss in complement-fixing activity was observed at glycation levels well comparable to those found in diabetics.
D000818:Animals; D003168:Complement Fixation Tests; D003920:Diabetes Mellitus / Q000276:immunology; D005662:Furaldehyde / Q000031:analogs & derivatives / Q000032:analysis / Q000276:immunology; D005947:Glucose / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology* / Q000302:isolation & purification; D066298:In Vitro Techniques; D011817:Rabbits; D006023:Glycoproteins
D005662:Furaldehyde; D005947:Glucose; D007074:Immunoglobulin G; C046179:glycosylated IgG; D006023:Glycoproteins; C008046:5-hydroxymethylfurfural