The cAMP assay: A functional in vitro alternative to the in vivo Histamine Sensitization test

Safety requirements stipulate the performance of the in vivo Histamine Sensitization (HS) test for quality control of acellular pertussis (aP) vaccines. For reasons of reproducibility and animal welfare concern, an in vitro assay was developed. The assay reflects the mechanism of histamine sensitization and is based on cAMP production in A10 cells to residual pertussis toxin (PT). We showed that PT induces cAMP levels in a dose-dependent manner while the sensitivity of the assay equals the sensitivity of the HS test. Neither the individual components nor the combination vaccine DTaP-IP did affect the assay. The cAMP assay meets the criteria for specificity and sensitivity and therefore might be a promising candidate to replace the HS test.