Failure of gamma-interferon to decrease mortality from group B streptococcal sepsis in neonatal rats

Newborns possess an altered immune response to infection with impaired leuk ocyte chemotaxis and deficient production of gamma-interferon (IFN-gamma). IFN-gamma enhances neonatal leukocyte activation and movement, We proposed that IFN-gamma in conjunction with penicillin compared to penicillin therap y without lFN-gamma would increase survival from group B streptococcal seps is in a neonatal rat model, Newborn rats were infected with 10(5) cfu of gr oup B streptococci at 48-72 h of age and randomized to receive either serum albumin (controls), rat recombinant IFN-gamma, albumin and penicillin, or IFN-V and penicillin, Survival 120 h postinfection revealed: controls 5% (1 /21); IFN-gamma 4% (1/24); penicillin 23% (5/22); and lFN-gamma plus penici llin 10% (2/21). Survival analysis with a lognormal parametric regression m odel revealed only the penicillin group to have improved survival compared to controls. Contrasting the penicillin group with the IFN-gamma plus penic illin group did not reveal a statistically significant difference by the Wa rd x(2) statistic (p = 0.25).