Humoral and cellular immune response of mice challenged with Yersinia pestis antigenic preparations

ABSTRACT Objectives: The plague, which is an infectious disease caused by Yersinia pestis, still threatens many populations in several countries. The worldwide increase in human plague cases and the potential use of the bacteria as a biological weapon reinforce the need to study the immunity that is induced by potential vaccine candidates. To determine the immunogenicity of antigenic preparations based on the F1 protein and the total extract from Y. pestis, we assessed the role of these antigens in inducing an immune response. Methods: The immunogenicity of antigenic preparations based on the Y. pestis (YP) total extract and the Y. pestis fraction 1 capsular antigen protein (F1) was determined in Swiss-Webster mice immunized with 40 µg or 20 µg for each preparation. Immunophenotyping was performed by flow cytometry. Results: Animals immunized with the YP total extract did not elicit detectable anti-F1 antibodies (Ab) in the hemaglutination/inhibition (HA/HI) test. Animals immunized with 40 µg or 20 µg of the F1 protein produced anti-F1 Abs, with titres ranging from 1/16 to 1/8132. The average of CD3+-CD4+ and CD3+-CD8+ T cells did not differ significantly between the groups. Neither YP total extract nor F1 protein induced a significant expression of IFN-γ and IL-10 in CD4+ T lymphocytes. In addition, F1 failed to induce IFN-γ expression in CD8+ T cells, unlike the YP total extract. Conclusion: The results showed that F1 protein is not an immunogenic T cell antigen, although the YP total extract (40 µg dose) favoured CD8+ T cell-mediated cellular immunity.

Evaluation of the immunotoxicological effects of Dimorphandra mollis Benth., Fabaceae, in rats / Avaliação dos efetos imunotoxicológicos de Dimorphandra mollis Benth., Fabaceae, em ratos

Dimorphandra mollis Benth., Fabaceae, also known as "faveira" or "fava-d'anta", is a plant common to the central woodsy meadow region of Brazil. It is well known for its antioxidant, antiplatelet and, principally, vasoprotective properties. Its principal component is rutin. The objective of this study is the evaluation of the safety of the use of the dried D. mollis extract in rodents. The rutin content of the standardized extract was 76.0±3 percent. With respect to the biochemical and hematological parameters evaluated, no alterations in the groups of rats that received 1000 and 2000 mg/kg doses of D. mollis were observed, but an increase in eosinophiles occurred. Hyperactivity of the white splenic pulp was detected in the group that received the 2000 mg/kg dose of D. mollis. In the evaluation of the lymphproliferative response with 1000 and 2000 mg/kg, no alterations were observed, and a decrease in IgG was only observed in the studies with a 2000 mg/kg dose. The results obtained with rodents suggest that no toxicity exists with the administration of dried D. mollis extract in a 1000 mg/kg dose.

A Dimorphandra mollis Benth., Fabaceae, conhecida como faveira ou fava-d'anta, é uma planta comum do cerrado central do Brasil, muito utilizada por suas propriedades antioxidante, antiplaquetária e, principalmente, como vasoprotetora. Seu principal marcador é a rutina. Este estudo teve como objetivo avaliar a segurança da utilização do extrato seco de D. mollis em roedores. O extrato foi extraído, padronizado e quantificado apresentando teor de 76,0±3 por cento de rutina. Nos parâmetros bioquímicos e hematológicos avaliados, não se observou alterações nos grupos de machos e fêmeas que receberam a dose de 1000 e 2000 mg/kg de D. mollis, mas observou-se um aumento de eosinófilos. Nos estudos histopatológicos detectou-se hiperreatividade da polpa branca esplênica, no grupo que recebeu a dose de 2000 mg/kg de D. mollis. Na avaliação da resposta linfoproliferativa, com 1000 e 2000 mg/kg não foram observadas alterações, e somente nos estudos com a dose de 2000 mg/kg se observou diminuição de IgG. Os resultados obtidos, utilizando roedores, sugerem que nenhuma toxicidade existe na administração de extrato seco de D. mollis na dose de 1000 mg/kg.