The modified leukocytosis promoting factor (LPF)-test: A valuable supplement to the mouse weight gain (MWG)-test in toxicity control of whole cell pertussis vaccine

For the safety testing of pertussis vaccine, many in vivo assays have been developed, but none of these assays, except the Mouse Weight Gain (MWG)-test, are obligatory. Leukocytosis Promoting Factor (LPF) test, performed in mice, is one of the tests to examine the toxicity. However, due to lack of standardization, this test has not been implemented in the regular safety testing of the vaccine. Our investigations demonstrate that the LPF-test becomes more reproducible and sensitive if preparations are administered subcutaneously on day 0 and and counting of the leukocytes are done on day 6. Therefore, it is suggested to include the revised LPF-test in the quality control panel for the assessment of the toxicity of whole-cell pertussis vaccine.