Epsilon-polylysine microparticle adjuvant drives cytokine production to Th1 profile

Epsilon-polylysine micro particles (SGEPL) and polyethyleneimine micro particles (SGPEI) were developed by the addition of a hydrophobic group and the immunological characterization of these micro particles and aluminum hydroxide (ALUM) was investigated. BALB/c mice were injected intraperitoneally with ovalbumin (OVA) as an antigen and SGEPL, SGPEI or ALUM as an adjuvant. The results showed that the mice injected with SGEPL produced a significant portion of anti-OVA antibody subclass IgG2a in the sera and suppressed interleukin (IL)-4 and IL-5, but enhanced IL-12 and interferon-gamma (IFN-gamma) from the spleen cells. Similar results relating to cytokines were also obtained, even without OVA. Direct stimulation with SGEPL to naïve BALB/c mouse spleen cells induced IL-12 and IFN-gamma. Both spleen and purified B cells produced IgG1 and IgE after stimulation with IL-4 and the anti-CD40 monoclonal antibody. With the addition of SGEPL, the IgE production from the cells was suppressed as a result of enhanced IFN-gamma production. Furthermore, IgE production was also suppressed in the purified B cells without the influence of IFN-gamma or IL-12. Thus, we suggest SGEPL drives cytokine production to Th1 profile. It will be a novel promising adjuvant based on this viewpoint.