title: Clonal restriction of platelet-associated anti-GPIIb/IIIa autoantibodies in patients with chronic ITP.
abstract: 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.
authors.affiliation: The Scripps Research Institute, La Jolla, California 92037, USA. mcmillan@scripps.edu
authors.forename: R
authors.initials: R
authors.lastname: McMillan
authors.forename: J
authors.initials: J
authors.lastname: Lopez-Dee
authors.forename: R
authors.initials: R
authors.lastname: Bowditch
mesh_terms: 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*
chemical_list: D001323:Autoantibodies; D000939:Epitopes; D007147:Immunoglobulin Light Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D019039:Platelet Glycoprotein GPIIb-IIIa Complex