GLYCOFORMS OF SERUM ALPHA-1-ACID GLYCOPROTEIN AS MARKERS OF INFLAMMATION AND CANCER

alpha 1-acid glycoprotein (AGP) is a serum acute phase glycoprotein wh ich possesses five N-linked complex type hetero-glycan side chains whi ch may be present as bi-, tri- and tetraantennary structures. Dependin g upon the content of biantennary structure on AGP, up to four glycofo rms of AGP are present in serum. These glycoforms can be easily estima ted in body fluids by means of crossed affinity-immunoelectrophoresis (CAIE) with the lectin, Concanavalin A (Con A). Con A selectively bind s biantennary structures; the more biantennary structures on AGP, the stronger the binding. In acute inflammation, a relative increase of AG P glycoforms with biantennary units is observed - a type I glycosylati on change. In some chronic inflammatory states there is an relative de crease of AGP glycoforms with biantennary heteroglycans - a type II gl ycosylation change. Moreover, in certain other states such as pregnanc y, estrogen administration or liver damage, type II glycosylation chan ges are also seen. A detailed analysis of the clinical applications of the assessment of AGP glycoforms in sera of patients with rheumatic d iseases, AIDS and various types of cancers is presented. Accumulated d ata shows that AGP glycoforms may be very useful in the detection of i ntercurrent infections in the course of rheumatoid arthritis, systemic lupus erythematosus, or myeloblastic leukaemia, and in the detection of secondary infections in human immunodeficiency virus infected indiv iduals. AGP glycoforms are also very useful in differentiation between various forms of trophoblastic disease and are helpful in monitoring the treatment of these patients. Finally, AGP glycoforms provide valua ble information for differentiation between primary and secondary live r cancer.