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Endotoxinaemia in sickle cell disease
1Department of Paediatrics, St Thomas's Hospital Medical School, London.
Insights
Endotoxemia, a bacterial toxin, may occur more often in children with sickle cell anemia who have impaired reticuloendothelial function. This suggests intestinal endotoxin absorption when immune function is low.
Area of Science:
- Hematology
- Immunology
- Pediatrics
Background:
- Sickle cell disease (SCD) encompasses sickle cell anemia (HbSS) and related hemoglobinopathies.
- Reticuloendothelial system (RES) dysfunction is a known complication of SCD.
- Endotoxemia, presence of bacterial endotoxins, is implicated in various inflammatory conditions.
Purpose of the Study:
- To investigate the prevalence of endotoxemia in children with SCD.
- To explore the association between RES function and endotoxemia in these patients.
Main Methods:
- Prospective study of 59 children with SCD (HbSS, HbSC, HbS-beta-thalassaemia).
- Chromogenic Limulus amoebocyte lysate assay used to detect circulating endotoxin.
- Reticuloendothelial function assessed by red cell pitting (≥2% pitted cells indicate dysfunction).
Main Results:
- Children with HbSS exhibited more severe disease markers than those with HbSC or HbS-beta-thalassaemia.
- Twenty-nine children with HbSS and RES dysfunction were identified.
- Three of these 29 children (10.3%) had detectable endotoxemia; all had HbSS.
- None of the 18 children with other sickle hemoglobinopathies and RES dysfunction showed endotoxemia.
Conclusions:
- Endotoxemia appears to be more prevalent in children with sickle cell anemia and compromised reticuloendothelial function.
- Findings support the hypothesis that impaired RES function facilitates intestinal endotoxin absorption.
- Further research is warranted to confirm the link between RES dysfunction, endotoxemia, and SCD severity.
Abstract:
Fifty-nine children with sickle cell anaemia (HbSS) or associated haemoglobinopathies were studied prospectively using a chromogenic Limulus amoebocyte lysate assay to detect circulating endotoxin. The 41 children with HbSS (mean age 8 years 9 months) had more serious disease than the 18 with HbSC disease (n = 14) or HbS-beta-thalassaemia (n = 4) (mean age 7 years 2 months), with a greater degree of splenomegaly, lower haemoglobin, and higher white cell counts, platelet counts and bilirubin values (P less than 0.05 for all). Twenty-nine children with HbSS had evidence of poor reticuloendothelial function, with red cell pitting of greater than or equal to 2%. Three of these 29 had low levels of endotoxin in plasma (0.12-0.24 endotoxin units (EU)/ml); two were clinically well, one had a painful crisis. Eight of 18 children with other sickle haemoglobinopathies had greater than or equal to 2% pitted red cells; none was endotoxinaemic. Therefore, in 37 patients with reticuloendothelial dysfunction, three were endotoxinaemic; all had sickle cell anaemia. Although not statistically significant, this suggests that endotoxinaemia may occur predominantly in patients with reticuloendothelial dysfunction, and is compatible with the hypothesis that systemic endotoxinaemia can derive from the intestine especially when reticuloendothelial function is depressed.