IgG subclass distribution of anti-ADAMTS13 antibodies in patients with acquired thrombotic thrombocytopenic purpura.
BACKGROUND
ADAMTS13-neutralizing IgG autoantibodies are the major cause of acquired thrombotic thrombocytopenic purpura (TTP).


OBJECTIVE
To analyze the IgG subclass distribution of anti-ADAMTS13 antibodies and a potential relationship between subclass distribution and disease prognosis.


METHODS
An enzyme-linked immunosorbent assay-based method was used to quantify the relative amounts of IgG subclasses of anti-ADAMTS13 antibodies in acquired TTP plasma.


RESULTS
IgG(4) (52/58, 90%) was the most prevalent IgG subclass in patients with acquired TTP, followed by IgG(1) (52%), IgG(2) (50%), and IgG(3) (33%). IgG(4) was found either alone (17/52) or with other IgG subclasses (35/52). IgG(4) was not detected in 10% of the patients. There was an inverse correlation between the frequency and abundance of IgG(4) and IgG(1) antibodies (P < 0.01). Patients with high IgG(4) levels and undetectable IgG(1) are more prone to relapse than patients with low IgG(4) levels and detectable IgG(1).


CONCLUSIONS
All IgG subclasses of anti-ADAMTS13 antibodies were detected in patients with acquired TTP, with IgG(4), followed by IgG(1), antibodies dominating the anti-ADAMTS13 immune response. Levels of IgG(4) could be useful for the identification of patients at risk of disease recurrence.
Ferrari
S
S
Department of Discovery Research and Technical Assessment, Baxter BioScience, 1220 Vienna, Austria.
Mudde
G C
GC
Rieger
M
M
Veyradier
A
A
Kremer Hovinga
J A
JA
Scheiflinger
F
F
D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000276:immunology*; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000145:classification* / Q000276:immunology; D001324:Autoantigens / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification* / Q000276:immunology; D007132:Immunoglobulin Isotypes / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000276:immunology; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000276:immunology; D011644:Puerperal Disorders / Q000276:immunology; D011697:Purpura, Thrombotic Thrombocytopenic / Q000276:immunology*; D055815:Young Adult
D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human