Acquired Glanzmann's thrombasthenia with optimal response to rituximab therapy

Acquired platelet function disorders

The possibility of an acquired platelet function disorder should be considered in patients who present with recent onset muco-cutaneous bleeding. Despite the availability of newer and faster platelet function assays, light transmission aggregometry (LTA) remains the preferred diagnostic test. This review examines and discusses the causes of acquired platelet dysfunction; most commonly drugs, dietary factors, medical disorders and procedures. In addition to well-known antiplatelet therapies, clinicians should be alert for newer drugs which can affect platelets, such as ibrutinib. There is little clinical trial evidence to guide the management of acquired platelet function defects, but we summarise commonly employed strategies, which include addressing the underlying cause, antifibrinolytic agents, desmopressin infusions, and in selected patients, platelet transfusions.

Acquired Glanzmann thrombasthenia: From antibodies to anti-platelet drugs

In contrast to the inherited platelet disorder given by mutations in the ITGA2B and ITGB3 genes, mucocutaneous bleeding from a spontaneous inhibition of normally expressed αIIbβ3 characterizes acquired Glanzmann thrombasthenia (GT). Classically, it is associated with autoantibodies or paraproteins that block platelet aggregation without causing a fall in platelet count. However, inhibitory antibodies to αIIbβ3 are widely associated with primary immune thrombocytopenia (ITP), occur in secondary ITP associated with leukemia and related disorders, solid cancers and myeloma, other autoimmune diseases, following organ transplantation while cytoplasmic dysregulation of αIIbβ3 function features in myeloproliferative and myelodysplastic syndromes. Antibodies to αIIbβ3 occur during viral and bacterial infections, while drug-dependent antibodies reacting with αIIbβ3 are a special case. Direct induction of acquired GT is a feature of therapies that block platelets in coronary artery disease. This review looks at these conditions, emphasizing molecular mechanisms, therapy, patient management and future directions for research.

A unique phenotype of acquired Glanzmann thrombasthenia due to non-function-blocking anti-αIIbβ3 autoantibodies

Essentials Acquired Glanzmann thrombasthenia (aGT) is generally caused by function-blocking antibodies (Abs). We demonstrated a unique aGT case due to marked reduction of αIIbβ3 with anti-αIIbβ3 Abs. The anti-αIIbβ3 Abs of the patient did not inhibit platelet function but reduced surface αIIbβ3. Internalization of αIIbβ3 induced by the Abs binding may be responsible for the phenotype. SUMMARY: Background Acquired Glanzmann thrombasthenia (aGT) is a bleeding disorder generally caused by function-blocking anti-αIIbβ3 autoantibodies. Aim We characterize an unusual case of aGT caused by marked reduction of surface αIIbβ3 with non-function-blocking anti-αIIbβ3 antibodies (Abs). Methods A 72-year-old male suffering from immune thrombocytopenia since his 50s showed exacerbation of bleeding symptom despite mild thrombocytopenia. Platelet aggregation was absent with all agonists but ristocetin. Analysis of αIIbβ3 expression and genetic analysis were performed. We also analyzed effects of anti-αIIbβ3 Abs of the patient on platelet function and αIIbβ3 expression. Results Surface αIIbβ3 expression was markedly reduced to around 5% of normal, whereas his platelets contained αIIbβ3 to the amount of 40-50% of normal. A substantial amount of fibrinogen was also detected in his platelets. There were no abnormalities in ITGA2B and ITGB3 cDNA. These results indicated that reduced surface αIIbβ3 expression caused a GT phenotype, and active internalization of αIIbβ3 was suggested. Anti-αIIbβ3 IgG Abs were detected in platelet eluate and plasma. These Abs did not inhibit PAC-1 binding, indicating that the Abs were non-function-blocking. Surface αIIbβ3 expression of a megakaryocytic cell line and cultured megakaryocytes tended to be impaired by incubation with the patient's Abs. After 2 years of aGT diagnosis, his bleeding symptom improved and surface αIIbβ3 expression was recovered to 20% of normal with reduction of anti-αIIbβ3 Abs. Conclusion We demonstrated a unique aGT phenotype due to marked reduction of surface αIIbβ3. Internalization induced by anti-αIIbβ3 Abs may be responsible in part for the phenotype.

Combination of acquired von Willebrand syndrome (AVWS) and Glanzmann thrombasthenia in monoclonal gammopathy of uncertain significance (MGUS), a case report

Background

Autoimmune paraphenomena, are associated with B-cell lymphoproliferative disorders, including monoclonal gammopathy of uncertain significance. These paraphenomena can rarely include acquired bleeding disorders.

Case presentation

This case study reports an unusual clinical presentation of 2 acquired bleeding disorders, Acquired von Willebrand syndrome (disease) and Acquired Glanzmann's thrombasthenia, in an elderly patient with monoclonal gammopathy of uncertain significance.

Conclusions

Acquired bleeding disorders are often underdiagnosed and a high degree of clinical suspicion is required. The patient in this study demonstrated platelet aggregometry which was atypical for isolated Glanzmann's thrombosthenia because of the severe concomitant endogenous decrease in von Willebrand factor. There was an absence of platelet aggregation to all tested agonists including ristocetin. Once the diagnosis was made, however, the patient showed a partial response to intravenous immunoglobulin confirming the immunological pathogenesis in this case. This case highlights the need to consider acquired bleeding disorders in patients with a possible predisposing factor.

Indication for allogeneic stem cell transplantation in Glanzmann’s thrombasthenia

Glanzmann’s thrombasthenia (GT) is an autosomal recessive disorder characterized by a lack of thrombocyte aggregation due to the absence of thrombocyte glycoproteins IIb and αIIbβ3. The role of haematopoietic stem cell transplantation (HSCT) in GT remains controversial. However, HSCT offers the only curative approach for patients with a severe clinical phenotype.

In this review, we will discuss the limitation of current status evidence and the specific risk of GT, in particular the alloimmunization and refractoriness to thrombocyte infusions. 19 successful HSCT in 18 GT type I patients have been reported. Mean age at transplantation was 5 years. All patients are still alive. The majority received sibling bone marrow transplant with busulfan and cyclophosphamid conditioning. GvHD incidence was within the normal range, but 10 patients showed alloimmunization of thrombocytes. Median follow up is 25 months.