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Elevated platelet‐associated IgG in SLE patients due to anti‐platelet autoantibody: differentiation between autoantibodies and immune complexes by ether elution
Author(s) -
Kurata Yoshiyuki,
Hayashi Satoru,
Kosugi Satoru,
Kashiwagi Hirokazu,
Tomiyama Yoshiaki,
Kanayama Yoshio,
Matsuzawa Yuji
Publication year - 1993
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1993.tb03215.x
Subject(s) - platelet , autoantibody , antibody , immunology , antigen , immune system , immune complex , chemistry , medicine
Summary The level of platelet‐associated IgG (PAIgG) is reported to be elevated in patients with systemic lupus erythematosus (SLE). However. the nature of PAIgG is unclear. We have investigated whether the PAIgG of SLE consists of anti‐platelet autoantibodies or immune complexes (IC). The PAIgG values measured by flow cytonietry were elevated in 11/25 patients with SLE. 3/6 SLE patients with thrombocytopenia had a high level of PAIgG (the mean fluorescence intensity >10). We used an ether elution technique to determine whether elevated PAIgG consists of anti‐platelet antibodies or IC. Preliminary experiments showed that the eluates prepared from platelets sensitized with anti‐HPA‐4a antibody reacted with normal platelets. while the eluates prepared from platelets sensitized with heat‐aggregated IgG or model IC failed to react with normal platelets. These results indicate that the reactivity of eluates can distinguish between platelet‐bound antibody and IC. We applied this technique to analysis of the PAIgG of SLE platelets. The eluates from SLE platelets (the mean fluorescence intensity > 10) reacted with normal platelets. indicating that the PAIgG of SLE platelets has the nature of anti‐platelet autoantibodies. Furthermore, we investigated the target antigens which bind PAIgGs of SLE, using the direct immunoprecipitation procedure and modified antigen capture ELISA (MACE). Both methods identified GPIIb/IIIa as the target antigens. We conclude that the ether elution technique can distinguish between anti‐platelet antibodies and TC. and that the PAIgGs of SLE with a high PAIgG value and thrombocytopenia have the nature of anti‐platelet autoantibodies.