A Differential Approach to an Uncommon Case of Acute Anemia in a Child With Sickle Cell Disease

Effect of lysed and non-lysed sickle red cells on the activation of NLRP3 inflammasome and LTB4 production by mononuclear cells

OBJECTIVE AND DESIGN

This study tested the hypothesis that sickle red blood cell (SS-RBC) can induce inflammasome NLRP3 components gene expression in peripheral blood mononuclear cells (PBMCs) as well as interleukin-1β (IL-1β) and leukotriene B4 (LTB4) production. Additionally, we investigated the effect of hydroxyurea (HU) treatment in these inflammatory markers.

METHODS

PBMCs from healthy donors (AA-PBMC) were challenged with intact and lysed RBCs from SCA patients (SS-RBC) and from healthy volunteers (AA-RBC). NLRP3, IL-1β, IL-18 and Caspase-1 gene expression levels were assessed by quantitative PCR (qPCR). IL-1β protein levels and LTB4 were measured by ELISA.

RESULTS

We observed that lysed SS-RBC induced the expression of inflammasome NLRP3 components, but this increase was more prominent for CASP1 and IL18 expression levels. Moreover, we observed that intact SS-RBC induced higher production of IL-1β and LTB4 than lysed SS-RBC. Although SCA patients treated with HU have a reduction in NLRP3 gene expression and LTB4 production, this treatment did not modulate the expression of other inflammasome components or IL-1β production.

CONCLUSIONS

Thus, our data suggest that caspase-1, IL-1β and IL-18 may contribute to the inflammatory status observed in SCA and that HU treatment may not interfere in this inflammatory pathway.

Hyperhemolysis Syndrome in a Patient with Sickle Cell Disease: A Case Report

Introduction

Hyperhemolysis syndrome (HHS) is a rare complication of repeat blood transfusions in sickle cell disease (SCD). This can occur acutely or have a delayed presentation and often goes unrecognized in the emergency department (ED) due to its rapid progression and similarity to acute chest syndrome and other common complications of SCD.

Case Report

We present a case of a 20-year-old male with SCD who presented to the ED with pain and tenderness in his lower extremities one day after discharge for a crisis. Unbeknownst to the ED team, during his admission he had received a blood transfusion. On presentation he was noted to have hyperkalemia, hyperbilirubinemia, anemia, and uncontrolled pain, and was admitted for sickle cell pain crisis. Over the next 36 hours, his hemoglobin dropped precipitously from 8.9 grams per deciliter (g/dL) to 4.2 g/dL (reference range: 11.5–14.5 g/dL), reticulocyte count from 11.7 % to 3.8% (0.4–2.2%), and platelets from 318,000 per cubic centimeter (K/cm³) to 65 K/cm³ (140–350 K/cm³). He also developed a fever, hypoxia, transaminitis, a deteriorating mental status, and severe lactic acidosis. Hematology was consulted and he was treated with methylprednisolone, intravenous immunoglobulin, two units of antigen-matched red blood cells, fresh frozen plasma, and cryoprecipitate. He was transferred to an outside hospital for exchange transfusion and remained hospitalized for 26 days with acute liver failure, bone marrow necrosis, and a fever of unknown origin.

Conclusion

Because of the untoward outcomes associated with delay in HHS diagnosis and the need for early initiation of steroids, it is important for emergency providers to screen patients with hemoglobinopathies for recent transfusion at ED presentation. Asking the simple question about when a patient’s last transfusion occurred can lead an emergency physician to include HHS in the differential and work-up of patients with sickle cell disease complications.

Hyperhaemolytic Syndrome in Sickle Cell Disease: Clearing the Cobwebs

Sickle cell disease (SCD) presents with a dynamic background of haemolysis and deepening anaemia. This increases the demand for transfusion if any additional strain on haemopoiesis is encountered due to any other physiological or pathological causes. Patients with cerebrovascular accidents are placed on chronic blood transfusion; those with acute sequestration and acute chest syndrome are likewise managed with blood transfusion. These patients are prone to develop complications of blood transfusion including alloimmunization and hyperhaemolytic syndrome (HHS). This term is used to describe haemolysis of both transfused and "own" red cells occurring during or post-transfusion in sickle cell patients. Hyperhaemolysis results in worsening post-transfusion haemoglobin due attendant haemolysis of both transfused and autologous red cells. The mechanism underlying this rare and usually fatal complication of SCD has been thought to be secondary to changes in the red cell membrane with associated immunological reactions against exposed cell membrane phospholipids. The predisposition to HHS in sickle cell is also varied and the search for a prediction pattern or value has been evasive. This review discusses the pathogenesis, risk factors and treatment of HHS, elaborating on what is known of this rare condition.