Efficacy of an immunomodulating drug in immunodeficient and immunocompetent mice.

Bacillus subtilis culture filtrate (BSKR) was examined for its immunomodulating ability in the immunodeficient beige mouse and the immunocompetent Han:NMRI mouse strain. Following various application schemes the mice were challenged either subcutaneously with Escherichia coli or intranasally with Streptococcus pneumoniae. The mortality rates and the median of survival time were determined. Following subcutaneous application of BSKR Han:NMRI mice challenged with E. coli showed a decrease in mortality regardless of the application scheme. Using the beige mouse a protective effect was observed only after single applications of relatively low doses. Using Sc. pneumoniae as the challenge organism, a subcutaneous application of BSKR caused a decrease in mortality only if it was given on the day prior to infection. In both infection models the intranasal application of BSKR and/or of saline proved to be beneficial by either significantly decreasing the mortality or considerably increasing the survival time of beige and Han:NMRI mice.