Estimation of Corynebacterium diphtheriae antitoxin in human sera: a comparison of an enzyme-linked immunosorbent assay with the toxin neutralisation test.
Serum samples from 101 individuals were titrated for Corynebacterium diphtheriae antitoxin by an IgG-specific enzyme-linked immunosorbent assay (ELISA) and a neutralisation test in tissue culture (TC). In some of the sera, the concentrations of antitoxin determined by the two assays were different; antitoxin values in these sera were titrated again by neutralisation tests in guinea pigs (GNT). Antitoxin concentrations of greater than 0.01 IU/ml by GNT partly corresponded to values obtained in both ELISA and TC. Only the values from TC agreed with lower GNT results. Heat inactivation of sera was investigated and rejected as a possible reason for the discrepancy in the results. ELISA can be used to detect levels of less than 0.1 IU/ml, although the accuracy below 0.01 IU/ml, often considered a protective level, is questionable. At higher levels ELISA was reproducible for the titration of diphtheria antitoxin in human sera and offers a useful alternative to both in-vivo assays and TC.
Melville-Smith
M
M
Division of Bacteriology, National Institute for Biological Standards and Control, South Mimms, Herts.
Balfour
A
A
D000818:Animals; D046508:Culture Techniques; D004166:Diphtheria Antitoxin / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D006168:Guinea Pigs; D006358:Hot Temperature; D006801:Humans; D009500:Neutralization Tests; D011237:Predictive Value of Tests
D004166:Diphtheria Antitoxin