Cytokine detection in splenocyte cultures. To detect IFN-γ (A), IL-4 (B) and IL-10 (C) production by ELISA, splenocyte cultures for each group of mice (n = 4) were prepared and the supernatants were collected after incubation for 48 h at 37°C with the PbCSP antigen (10 or 50 μg/ml), 0.5 μg/ml of concanavalin A (ConA) or without any stimulus. Each bar represents the mean ± SD based on four mice per group. Mice were either immunized by OML-PbCSP (OML-PbCSP), OML alone (OML-PBS), naked PbCSP (PbCSP), or not immunized (None). Different superscript letters indicate statistically significant differences (P <0.05) among groups as determined by a one-way analysis of variance followed by Tukey’s multiple comparison test.