PCEP significantly enhances IFN-g and IL-4 cytokine production in mice immunized via intranasal route. The spleens from mice immunized with PCEP+X:31 (closed bars) or X:31 alone (open bars) were collected and splenocytes were subsequently isolated. The splenocytes were stimulated with X:31 antigen and antigen-specific IFN-γ (A) and IL-4 (B) were assayed to determine Th1/Th2 responses. Differences in cytokine production as a result of IN, SC, oral, or IR immunization were also examined. Different letters indicate significant differences between groups that received PCEP+X:31, while asterisks indicate significant differences between PCEP+X:31 compared to X:31 antigen alone (p < 0.05).