Anti-Factor H is a highly specific enzyme immunoassay for the quantitative determination of IgG autoantibodies against factor H, in human serum or plasma.
Hemolytic uremic syndrome (HUS) is a disease of the small blood vessels, characterized by hemolytic anemia, thromocytopenia and acute renal failure (incidence in children in Central Europe is 7 in 1 million). The most common cause is infection with toxin producing Escherichia coli strains (shiga toxin, vero toxin). Up to 10 % of severe manifestations are fatal. Approximately 5 % of HUS patients show no signs of E. Coli infection, and also do not present diarrheal diseas. This so-called atypical HUS is caused by a disturbance in the regulation of the alternative complement system. In addition to mutation of the genes of the complement system, an acquired dysfunction of the complement regulator factor H through targeted antibodies can be a cause. According to an international consensus agreement (Loirat et al. 2015), all patients with suspected atypical HUS are to be tested for these antibodies before treatment, such as plasmapheresis, is initiated.
Anti-Factor H is a highly specific enzyme immunoassay for the quantitative determination of IgG autoantibodies against factor H, in human serum or plasma. As there is no international reference material, the factor H ELISA is calibrated in arbitratry units (U/ml). The cut off of the factor H ELISA is ≥ 10 U/ml, and the analytical sensitivity is 1 U/ml. Upon testing 93 serum samples from healthy blood donors, 4 samples were found to be above the cut off. Therefore the specificity is 95.7 %. Upon testing 13 sera from patients with atypical hemolytic uremic syndrome, which were tested positive with a reference test, 12 were also positive with the anti-H ELISA. This corresponds to a relative sensitivity of 92.3 %.
|Assay Principle||Enzyme immunoassay, ELISA|
|Assay Size||48 determinations|
|Indication||Atypical hemolytic uremic syndrome|
|Parameter||IgG antibodies against factor H|
|Preparation||Dilution of patient samples 1:100 with sample diluent. Standards and controls are ready for use.|
|Results||Quantitative: U/ml Cut-off: ≥ 10 U/ml|
|Incubation Times||60 min RT - 30 min RT - 15 min RT in the dark|
|Substrate||Tetramethylbenzidine (TMB), 450 nm|
|Sample Material||Human serum or plasma|
Loirat, C., Fakhouri, F., Ariceta, G., Besbas, N., Bitzan, M., Bjerre, A., Coppo, R., Emma, F., Johnson, S., Karpman, D., Landau, D., Langman, C.B., Lapeyraque, A.L., Licht, C., Nester, C., Pecoraro, C., Riedl, M., van de Kar, N.C., van de Walle, J., Vivarelli, M., Frémeaux-Bacchi, V. for HUS International. An international consensus approach to the management of atypical hemolytic uremic syndrome in children. Pediatr Nephrol. 2016 Jan; 31 (1): 15-39.