Endotoxinaemia in sickle cell disease.

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.