Kaninchen-Ergänzung UnadsoRabbited 100 ml

Complement-mediated bactericidal antibodies in serum confer protection against meningococcal disease. The minimum protective titer is estimated to be between 1:4 and 1:8 when measured using the Goldschneider assay performed with human complement, the assay used in the 1960s to measure the correlation between bactericidal antibodies and determine protection.  A recently described bactericidal assay, standardized by an international consortium, uses rabbit complement, which is known to increase bactericidal titers. 

To define a protective titer measured by the standardized assay, we compared bactericidal titers against serogroup C strains measured by this assay with titers measured by the method described by Goldschneider et al.

•  A titer of ≥1:128 as measured by the standardized assay was required to predict with ≥80% confidence a positive titer of ≥1:4 as measured by the Goldschneider assay. However, the majority of samples with titers of 1:4 as measured by the Goldschneider assay had titers of <1:128 as measured by the standardized assay. Therefore, such individuals would be misclassified as susceptible to disease by the results of the standardized assay. In conclusion, high bactericidal titers measured with the standardized assay performed with rabbit complement predict protection, but no threshold titer is both sensitive and specific for predicting a positive titer, measured by the Goldschneider assay using human complement. Up to 10% of the US adult population lack intrinsic bactericidal activity against serum serogroup C strains and can serve as complement donors. Because of this,
• Considerable data support a relationship between the presence of complement-mediated bactericidal antibodies in serum and protection from the development of invasive meningococcal disease (reviewed by Frasch).
• Therefore, there is strong scientific rationale for inferring the efficacy of a new meningococcal vaccine from immunogenicity data. However, this approach is based on the premise that the method used to test bactericidal antibodies yields clinically relevant titers that have been linked to supporting epidemiological and/or experimental studies.
• In a landmark study on the role of serum bactericidal antibodies and protection against meningococcal disease, Goldschneider et al. received baseline serum samples from unimmunized military recruits who were at high risk of developing serogroup C disease during their 8-week participation in the training camp. 
• A baseline serum bactericidal titre of ≥1:4 was a strong predictor of protection. Subsequently, some experts recommended using a titer ≥ 1:8 as the threshold for defining protection (Carl Frasch, personal communication), on the grounds that the higher titer offers a greater safety margin when assessing protection. In general, a titer of ≥ 1:4 is accepted as a protective threshold titer in Europe, while a titre of ≥ 1:8 is used in the United States.