The imipenem/cilastatin constitutes a broad spectrum beta-lactam antib
iotic formulation, especially used in pre and post-operatory treatment
s for transplanted or drug-immunosuppresed patients. The effect of the
dose and the duration of the treatment with imipenem/cilastatin on so
me parameters of natural immunity in BALB/c mice were examined. The tr
eatment by intraperitoneal route with 1 or 2 g/70 kg/day during 7 days
did not alter significantly the parameters tested, whereas the greate
r dose used (4 g/70 kg/day) had an inhibitory effect on peritoneal cel
l counts and phagocytic activity, as well as it caused an increase on
IL-1 production and natural killer activity. The greater stimulating e
ffect of innate immunity was obtained with the lowest imipenem/cilasta
tin dose used (0.5 g/70 kg/day). Since this antibiotic apparently does
not impair the studied innate immune responses at 1 or 2 g/70 kg/day,
it seems to be especially suited for the therapy of systemic bacteria
l infections in immunocompromised patients.