Clonal restriction of platelet-associated anti-GPIIb/IIIa autoantibodies in patients with chronic ITP.
Chronic immune thrombocytopenic purpura is due to platelet destruction induced by autoantibodies against platelet surface antigens. Prior studies show that some serum autoantibodies are light-chain restricted, suggesting a clonal origin. Since plasma and platelet-associated antibody from the same patient may bind to different epitopes. it is important to evaluate the clonality of platelet-associated antibody. Platelet-associated autoantibodies from 28 ITP patients were studied. Of 23 platelet-associated antibodies tested directly, 16 showed significant light chain restriction (7 complete and 9 partial) when compared to plasma IgG light chain distribution. Similarly, 9 of 12 platelet-associated antibody eluates were light chain restricted, 5 complete and 4 partial. In all cases where platelet-associated antibody and antibody eluate from the same patient were studied, the results were concordant. We conclude that a significant proportion of platelet-associated antibodies from ITP patients show apparent clonality, as evaluated by light chain restriction. These results are consistent with other studies in ITP suggesting a limited antigenic repertoire.
McMillan
R
R
The Scripps Research Institute, La Jolla, California 92037, USA. mcmillan@scripps.edu
Lopez-Dee
J
J
Bowditch
R
R
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000737:chemistry; D001792:Blood Platelets / Q000276:immunology; D002908:Chronic Disease; D002999:Clone Cells / Q000276:immunology / Q000473:pathology*; D000939:Epitopes; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood; D007145:Immunoglobulin kappa-Chains / Q000097:blood; D007146:Immunoglobulin lambda-Chains / Q000097:blood; D008297:Male; D008875:Middle Aged; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000209:etiology / Q000276:immunology*
D001323:Autoantibodies; D000939:Epitopes; D007147:Immunoglobulin Light Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D019039:Platelet Glycoprotein GPIIb-IIIa Complex