Levels of malaria-specific antibodies in the sera of A/J mice immunized s.c. with antigen (Ag) alone, antigen in alum, antigen plus IL-12, or antigen plus IL-12 in alum and boosted 3 weeks later by i.p. injection with antigen. Two weeks later, sera were collected from immunized mice and the levels of total malaria-specific antibody, IgG1, and IgG2a were determined by ELISA. Data represent OD values for individual mice and are pooled from 2 experiments.