Opsonizing antibodies, host factors, and the limulus assay for endotoxin.
The role of endotoxin in the pathophysiology of human gram-negative rod bacteremia is controversial. Gelation of lysates prepared from the amebocytes of Limulus polyphemus is a highly sensitive means for quantifying endotoxin-like activity in vitro, but variable results have been reported in several clinical studies. We performed limulus tests on plasmas obtained simultaneously with culture-positive blood from 68 patients with gram-negative bacteremia and related results to heat-stable opsonizing activity against the autologous infection strain. Overall, limulus positivity was 52% in this series. Positive tests were observed with 78% of plasmas with opsonic titers is less than or greater to 1:20 but with only 27% of plasmas whose titers were is greater than or equal to 1:80 (P less than 0.005). There was a strong association of positive tests with leukopenia. thrombocytopenia, and more severe underlying disease. In vitro study showed a 10-fold reduction in the sensitivity of the gelation test by antibodies against the endotoxin used and an additional 10-fold reduction when the test system included phagocytic cells.
D000907:Antibodies, Bacterial; D001419:Bacteria; D004731:Endotoxins / Q000032:analysis*; D005782:Gels; D007970:Leukopenia / Q000175:diagnosis; D008974:Mollusca; D009895:Opsonin Proteins / Q000032:analysis*; D010586:Phagocytes; D012475:Salmonella / Q000276:immunology; D018805:Sepsis / Q000175:diagnosis; D013921:Thrombocytopenia / Q000175:diagnosis
D000907:Antibodies, Bacterial; D004731:Endotoxins; D005782:Gels; D009895:Opsonin Proteins