FIG. 1.

rhPRL improves production of DT-specific IgG after DT vaccine rechallenge of huPBL-SCID mice. huPBL-SCID mice were created and immunized as described in Materials and Methods. Ten micrograms of rhPRL or HBSS was injected i.p. every other day for a total of 20 days. On day 28 after huPBL transfer, sera were analyzed using a DT-specific ELISA as described in Materials and Methods. The experiment had four or five mice per group. The results are expressed in optical density units, as assessed on a spectrophotometer at 450 nm from a 1:100 dilution of each sample. rhPRL significantly (P < 0.05 for 0 μg and 10 μg of DT vaccine; P < 0.01 for 0.1 μg and 1 μg of DT vaccine) promoted DT-specific IgG production after rechallenge with DT immunization. **, P < 0.01; *, P < 0.05 (comparing PRL with HBSS group in response to DT injection).