The protein moiety of the Brucella Omp19 lipoprotein, co-administered as oral adjuvant, induces a Th1 immune response

IBAÑEZ, ANDRES; CORIA, LORENA; PASQUEVICH, KARINA; BARRIONUEVO, PAULA; DELPINO M. VICTORIA; GIAMBARTOLOMEI, GUILLERMO; CASSATARO, JULIANA

Buenos Aires, Argentina

Congreso; First French Argentine Immunology Congress; 2010

Previous results demonstrate that the protein moiety of the Brucella Omp19 lipoprotein (U-Omp19) administered by the oral route has self-adjuvant properties. These prompt us to study its mucosal adjuvant capacity using as a model antigen ovalbumin (OVA). For this purpose mice were immunized orally with OVA, U-Omp19+OVA, or choleric toxin (CT)+OVA. By flow cytometry we determined that the percentage of CD4+ and CD8+ T cells expressing alpha4beta7 integrin increased in those mesenteric lymph nodes from U-Omp19+OVA (CD4+ alpha4beta7+: 7,7%; CD8+ apha4beta7+:12,16%) and CT+OVA (7,15%; 16,46%) in comparison with OVA (0,74%; 1,64%) immunized mice. We also observed a significant delayed type hypersensitivity (DTH) response to OVA injection in U-Omp19+OVA (Ä=0,11mm, P<0.01 vs OVA immunized group) and CT+OVA (Ä=0,07mm P<0.05 vs OVA) while OVA (Ä=0,01mm) group did not. Similarly, splenocytes from mice immunized orally with U-Omp19+OVA secreted significant amounts of IFN-ã (1045,8 pg/ml, P<0.05 vs OVA immunized group) in response to OVA. In contrast, IFN-g levels secreted by the CT+OVA group (322.8pg/ml) were similar to the OVA (448.5pg/ml) immunized group. On the other hand, there was no production of Th2 (IL-4) or Th3 (IL-10) cytokines in response to OVA in any immunized mice. We also observed an increase in IL-17 production in response to OVA by the splenocytes of U-Omp19+OVA immunized mice, but this increase was not statistically different from OVA immunized group (P>0.05). By flow cytometry we determined that the percentage of CD4+ and CD8+ T cells producing intracellular IFN-g -in response to OVA- increased in U-Omp19+OVA (CD4+IFN-g+ 2.13%; CD8+IFN-g+ 0.77%)  in comparison with CT+OVA (0.45%; 0.55%) and OVA (0.41%; 0.37%) vaccinated mice. In conclusion, U-Omp19 as oral adjuvant induces the migration of CD4+ and CD8+ T cells to gastrointestinal lamina propria, T cells responses in vivo and CD4+ and CD8+ T cells that produce IFN-g in response to OVA.