Autoantibodies to thrombopoietin and the thrombopoietin receptor in patients with immune thrombocytopenia

Br J Haematol. 2018 Apr;181(2):234-241. doi: 10.1111/bjh.15165. Epub 2018 Mar 13.

Abstract

Autoantibodies to thrombopoietin (TPO, also termed THPO) or the TPO receptor (cMpl, also termed MPL) could play a pathological role in immune thrombocytopenia (ITP). In this study, we tested for autoantibodies against TPO, cMpl, or the TPO/cMpl complex in ITP and other thrombocytopenic disorders. Using an inhibition step with excess TPO in fluid-phase to improve binding specificity, the prevalence of anti-TPO autoantibodies was: active ITP: 9/32 (28%); remission ITP: 0/14 (0%); non-immune thrombocytopenias: 1/10 (10%); and healthy controls: 1/11 (9%). Similarly, using an inhibition step with excess cMpl, the prevalence of specific anti-cMpl autoantibodies was: active ITP: 7/32 (22%); remission ITP: 1/14 (7%); non-immune thrombocytopenias: 3/10 (30%); and healthy controls: 0/11 (0%). Two active ITP patients had autoantibodies against the TPO/cMpl complex, but not against TPO or cMpl alone. Anti-TPO or anti-cMpl autoantibodies were found in 44% of ITP patients, and in 40% of patients with other thrombocytopenic disorders. These autoantibodies did not correlate with ITP disease severity or number of ITP treatments received; however, in this cohort, 3 patients failed to respond to TPO receptor agonist medications, and of those, 2 had anti-TPO autoantibodies. This suggests that anti-TPO and anti-cMpl autoantibodies are associated with thrombocytopenia, and may be clinically relevant in a subset of ITP patients.

Keywords: autoantibodies; cMpl; glycoproteins; immune thrombocytopenia; thrombopoietin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Autoantibodies* / blood
  • Autoantibodies* / immunology
  • Female
  • Humans
  • Male
  • Purpura, Thrombocytopenic, Idiopathic* / blood
  • Purpura, Thrombocytopenic, Idiopathic* / drug therapy
  • Purpura, Thrombocytopenic, Idiopathic* / immunology
  • Receptors, Thrombopoietin* / agonists
  • Receptors, Thrombopoietin* / blood
  • Receptors, Thrombopoietin* / immunology
  • Severity of Illness Index

Substances

  • Autoantibodies
  • Receptors, Thrombopoietin
  • MPL protein, human

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