FIG. 9.

Neonatal administration of OM-85 enhances priming for subsequent DTH responses. Newborn rat pups were given OM-85 (n = 6) or placebo (n = 7; 400 μg/ml per g of body weight) and immunized s.c. with 25 μg of OVA in IFA. OM-85 or placebo was given each day for 14 days after immunization and then every second day until day 28. On this day, feeding treatments were withdrawn, and each animal received 100 μg of OVA in PBS i.p. After another 4 weeks, rats (now 8 weeks old) were injected i.d. in the right ear with OVA in PBS and in the left ear with PBS alone. Unimmunized age-matched control rats (n = 6) were injected i.d. with OVA in PBS and with PBS alone in order to establish background swelling responses. Twenty-four hours later, skin swelling of both ears was measured with a micrometer. The left ear thickness (PBS) was subtracted from the right ear thickness (OVA) to give increments of ear swelling. Ears of untouched animals (n = 4) were measured in order to establish background variation. The data are representative of five separate experiments, and each bar represents the mean difference in ear swelling ± standard error. Mann-Whitney U test-generated P values indicate significant differences in ear swelling due to administration of OM-85 (∗, 0.05 > P > 0.01).