B and T lymphocytes in acquired Thrombotic Thrombocytopenic Purpura during disease remission

Alemtuzumab-induced immune-mediated thrombotic thrombocytopenic purpura: A newly described drug-related autoimmune disease

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disease that may result from drug exposure. We report a case of iTTP occurring in a 39-year-old patient, 45 months following introduction of the anti-CD52 lymphoid cell depleting monoclonal antibody alemtuzumab, to treat a relapsing-remitting multiple sclerosis. Treatment consisted in plasma exchange, corticosteroids and caplacizumab, allowing clinical remission 3 months after the diagnosis, attested by the absence of thrombocytopenia and recovery of ADAMTS-13 activity. As other autoimmune disorders, iTTP may occur following alemtuzumab. This diagnosis should be suspected in patients with features of thrombotic microangiopathy following this treatment.

Connective Tissue Disorders in Patients With Thrombotic Thrombocytopenic Purpura: A Retrospective Analysis Using a National Database

Background

Prior reports have shown acquired thrombotic thrombocytopenic purpura (TTP) co-existing with connective tissue disorders (CTD). However, these are mainly limited to case reports and case-series reports, and the patient characteristics and clinical outcomes in these patients are not well known.

Methods

We used National Inpatient Sample and Nationwide Inpatient Sample (NIS) database for the years 2009 to 2016 to identify all adult patients with TTP and searched for either the presence or absence of any co-existing CTD. These two cohorts of TTP patients were then compared using statistical methods for baseline patient characteristics and clinical outcomes. The primary outcome of interest was the all-cause in-hospital mortality and the secondary outcomes were in-hospital length of stay, in-hospital total charge and in-hospital complications.

Results

Of the 14,400 cases of TTP diagnosed between 2009 and 2016, nearly 9% (n = 1,247) had one or more underlying CTD. Patients with TTP were more likely to be young, black, female, with more than one comorbidity and with private insurance if they had an underlying CTD than when they did not have any underlying CTD. There was no difference in regards to the size, location or type of the hospital, or the time taken to initiate plasmapheresis. Patients being managed for TTP had a longer mean length of hospital stay and a greater mean total inpatient stay charge if they had underlying CTD. There was however no difference in the risks of inpatient mortality, acute coronary syndrome, cardiac arrest, acute stroke, need for mechanical ventilation or hemodialysis.

Conclusion

TTP and CTD frequently co-existed and contributed to a longer hospital stay and a greater hospital charge.

Acquired thrombotic thrombocytopenic purpura

The von Willebrand factor (VWF)-cleaving metalloprotease, ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motifs-13) is the only known target of the dysregulated immune response in acquired TTP. Autoantibodies to ADAMTS13 either neutralize its activity or accelerate its clearance, thereby causing a severe deficiency of ADAMTS13 in plasma. As a consequence, size regulation of VWF is impaired and the persistence of ultra-large VWF (ULVWF) multimers facilitates micro vascular platelet aggregation causing microangiopathic haemolytic anaemia and ischaemic organ damage. Autoimmune TTP although a rare disease with an annual incidence of 1.72 cases has a mortality rate of 20% even with adequate therapy.

We describe the mechanisms involved in ADAMTS13 autoimmunity with a focus on the role of B- and T-cells in the pathogenesis of this disorder. We discuss the potential translation of recent experimental findings into future therapeutic concepts for the treatment of acquired TTP.

Risk factors and clinical profile of thrombotic thrombocytopenic purpura in systemic lupus erythematosus patients. Is this a distinctive clinical entity in the thrombotic microangiopathy spectrum?: a case control study

INTRODUCTION

The association of thrombotic thrombocytopenic purpura (TTP) with systemic lupus erythematosus (SLE) is rare. It is associated with high morbidity and mortality. Information about risk factors and clinical outcomes is scant.

MATERIAL AND METHODS

A retrospective case-control study was performed in a referral center in Mexico City between 1994 and 2013. Patients were diagnosed with TTP if they fulfilled the following criteria: microangiopathic haemolytic anaemia, thrombocytopenia, high LDH levels, normal fibrinogen and negative Coombs' test. Patients with SLE were diagnosed with ≥ 4 ACR criteria. We included three study groups: group A included patients with SLE-associated TTP (TTP/SLE; cases n = 22, TTP events n = 24); patients with non-autoimmune TTP (NA-TTP; cases n = 19, TTP events n = 22) were included in group B and patients with SLE without TTP (n = 48) in group C.

RESULTS

After multivariate analysis, lymphopenia < 1000/mm3 [OR 19.84, p = 0.037], high SLEDAI score three months prior to hospitalisation [OR 1.54, p = 0.028], Hg <7g/dL [OR 6.81, p = 0.026], low levels of indirect bilirubin [OR 0.51, p = 0.007], and less severe thrombocytopenia [OR 0.98, p = 0.009] were associated with TTP in SLE patients. Patients with TTP/SLE received increased cumulative steroid dose vs. NA-TTP (p = 0.006) and a higher number of immunosuppressive drugs (p = 0.015). Patients with TTP/SLE had higher survival than NA-TTP (p=0.033); however, patients hospitalised for TTP/SLE had a higher risk of death than lupus patients hospitalised for other causes

CONCLUSIONS

Lymphopenia is an independent risk factor for TTP/SLE. It is likely that patients with TTP/SLE present with less evident clinical features, so the level of suspicion must be higher to avoid delay in treatment.

Preferential HLA-DRB1*11–dependent presentation of CUB2-derived peptides by ADAMTS13-pulsed dendritic cells

ADAMTS13 derived peptides presented on HLA-DR; implications for acquired TTP. CUB2 domain peptide binds to risk-allele HLA-DRB1*11.