Detection of basophil-activating IgG autoantibodies in chronic idiopathic urticaria by induction of CD 63.
BACKGROUND
Approximately 40% to 50% of patients with chronic idiopathic urticaria (CIU) have functional IgG autoantibodies against FcepsilonRIalpha or IgE, which induce histamine release from basophils and cutaneous mast cells. A positive autologous serum skin test response is believed to reflect the presence of these autoantibodies.


OBJECTIVE
We sought to further define the functional properties of and develop a sensitive functional assay for detection of autoantibodies in patients with CIU.


METHODS
Sera from patients with CIU (n=61) and sera from healthy control subjects (n=23) were incubated with donor basophils. Activation of basophils was determined on the basis of CD 63 surface expression, as analyzed on a FACScan flow cytometer.


RESULTS
A positive basophil activation test result was found in 51% of patients with CIU, and basophil-activating properties were present in the IgG fractions of sera. When both the in vitro test and the autologous serum skin test were considered, basophil/mast cell-activating autoantibodies were present in 62% of the patients. Patients with a positive basophil activation test result had a significantly higher prevalence of other autoantibodies, had more severe urticaria, and were more likely to have angioedema.


CONCLUSIONS
The results demonstrate the presence of basophil-activating autoantibodies in about 50% of patients with CIU. The data support the autoimmune cause of the disease and provide a simple test for detection of these autoantibodies.
De Swerdt
Ann
A
Division of Clinical Immunology, University Hospital, Katholieke Universiteit Leuven, Belgium.
Van Den Keybus
Caroline
C
Kasran
Ahmad
A
Cadot
Pascal
P
Neyens
Karen
K
Coorevits
Lieve
L
Kochuyt
Anne-Marie
AM
Degreef
Hugo
H
Ceuppens
Jan L
JL
D000293:Adolescent; D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology* / Q000378:metabolism; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001491:Basophils / Q000276:immunology*; D002908:Chronic Disease; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007158:Immunologic Techniques; D010980:Platelet Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D017455:Receptors, IgE / Q000276:immunology; D012882:Skin Tests; D060149:Tetraspanin 30; D014581:Urticaria / Q000097:blood / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D015703:Antigens, CD; D001323:Autoantibodies; C554586:CD63 protein, human; D007074:Immunoglobulin G; D010980:Platelet Membrane Glycoproteins; D017455:Receptors, IgE; D060149:Tetraspanin 30; D007073:Immunoglobulin E