Interleukin-12 alters helper T-cell subsets and antibody profiles induced by the mucosal adjuvant cholera toxin

Factors that Influence the Immunological Adjuvant Effect of Lactobacillus fermentum PC1 on Specific Immune Responses in Mice to Orally Administered Antigens

This study examined the influences of the dosage of the adjuvant, the nature of the antigen and the host genetics on the capacity of L. fermentum PC1 (PC1) to function as an oral adjuvant. BALB/c and DBA/1 mice were vaccinated with either ovalbumin (OVA) or Salmonella Typhimurium on days 0 and 14, Mice were also dosed with the PC1 (10⁸ CFU or 10¹¹ CFU per dose per mouse) with the antigens (days 0 and 14) and alone (days −1 and 13). The higher PC1 dose elicited a greater specific serum IgG2a response than IgG1 for both antigens and mice strains, indicating a Th1-biased humoral immune response. The Th1 bias was also observed at the cellular level with greater specific IFN-γ levels than IL-4 and IL-10 with both antigen types and mouse strains. With the particulate antigen, the lower dose of PC1 elicited a Th1 bias at the cellular level, but a balanced Th1/Th2 response at the systemic humoral level. With the soluble antigen, a strong Th1-biased response occurred at the cellular level while the systemic humoral response was Th2-biased. In conclusion, PC1 at the higher dose was an excellent Th1 adjuvant, which was unaffected by the nature of the antigen or the host’s genetic background.

CpG DNA as mucosal adjuvant

We have previously found synthetic oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs to be a potent adjuvant to protein administered by intramuscular injection or intranasal inhalation to BALB/c mice. Herein we have further evaluated the potential of CpG ODN as a mucosal adjuvant to purified hepatitis B surface antigen (HBsAg) when administered alone or with cholera toxin (CT). CpG ODN and CT both augmented systemic (humoral and cellular) and mucosal immune responses against HBsAg, and these could be further enhanced with higher doses of adjuvant or boosting. Overall, antibody isotypes with CT alone were predominantly IgG1 (Th2-like) whereas they were predominantly IgG2a (Th1-like) with CpG ODN alone or in combination with CT. Results from this study indicate that stimulatory CpG ODN are promising new adjuvants for mucosal vaccination strategies, whether used alone or in combination with other mucosal adjuvants.

Interleukin-12 as an adjuvant for cancer immunotherapy

Interleukin-12 (IL-12) is a cytokine whose main effect is to drive Th-cell differentiation throughout a T helper type 1 cell type of response, thus inducing interferon gamma (IFNgamma) and favoring a switch from Ig to IgG2a. These properties make IL-12 a candidate adjuvant for vaccination against cancer and infection disease. Enthusiasm was generated in many animal studies where IL-12 was given either systemically or locally. The experience of some toxicity in humans has hampered its further development into clinical applications, which, however, are still possible if restricted to local administration. Gene transfer seems to be the preferred approach to obtain this local release of cytokine. Here we review the applications of IL-12 as adjuvant.

Cutting Edge: CpG DNA Is a Potent Enhancer of Systemic and Mucosal Immune Responses Against Hepatitis B Surface Antigen with Intranasal Administration to Mice

Mucosal immunity is difficult to induce with subunit vaccines unless such vaccines are administered with a mucosal adjuvant such as cholera toxin (CT); however, CT is toxic in humans. Synthetic oligodeoxynucleotides containing immunostimulatory CpG motifs (CpG) are potent adjuvants for the induction of Th1-like systemic immune responses against parenterally delivered proteins. Here, we show in mice that intranasal delivery of hepatitis B surface Ag, which alone has no effect, elicits good immune responses when given with CpG oligodeoxynucleotides and/or CT. Overall, CpG is superior to CT for the induction of humoral and cell-mediated systemic immunity as well as mucosal immune responses (IgA) at local (lung) and distant (feces) sites. Furthermore, CpG and CT act synergistically, giving stronger responses than those observed with 10 times more of either adjuvant alone. Ab isotypes were predominantly IgG1 (Th2-like) with CT, mixed IgG1/IgG2a (Th0) with CpG, and predominantly IgG2a (Th1-like) with CpG and CT together.