Papel das citocinas IL-5 e IL-17A na diferenciação de células produtoras de anticorpos de vida longa (ASC) induzida pelo veneno do peixe Thalassophryne nattereri

Abstract

GRUND, L. Z. THE ROLE OF IL-5 AND IL-17A IN THE DIFFERENTIATION OF LONG-LIVED ANTIBODY SECRETING CELLS (ASC) INDUCED BY Thalassophryne nattereri FISH VENOM. 2009. 115 f. Master thesis (Immunology) – Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, 2009. We demonstrated recently that T. nattereri fish venom is able to induce a memory immune response with a production of high levels of IL-5 and venomspecific IgG for six months after immunization and the differentiation of B cells B220neg, an indicative of long-lived antibody-secreting cells ASC. Thus we proposed here to assess the in vivo effect of the venom on memory response analyzing the B1a cells and ASC differentiating in different compartments (peritoneum, spleen and bone marrow). The factors involved in the maintenance of memory response and the role of cytokine IL-5 and IL-17A in the differentiation and maintenance of ASC were also evaluated. Balb/c mice immunized twice (days 0 and 14) with 10 μg of venom adsorbed in alum were bled and killed at days 21, 28, 48, 74 and 120 to detection of antibodies by Elisa and PCA and of B cell subtypes by flow cytometry. The results showed that venom promoted splenomegaly accompanied by intense cell proliferation and germinal centers formation for 120 days after immunization and induced high and persistent production of venom-specific IgG1, IgG2a and IgE. Furthermore, we observed an expansion of B1a cells in the peritoneum cavity and spleen. Based on the expression of CD43 and B220 in CD138pos ASC, we reveal five subtypes of memory B cells (B220high CD43high, B220low CD43low, B220neg CD43low, B220low CD43high, and B220neg CD43high) in all compartments. The production of inflammatory cytokines and chemokines (KC, TNF-α, IL-1β, IL-6), the secretion of high levels of IL-5 and IL-17A by cells of the all compartments, as well as the large amounts of venom retained in the surface of follicular dendritic cells (FDCs) in spleen seem to provide a special microenvironment to maintenance of ASC. Finally, to address the role of cytokines IL-5 and IL-17A in persistent memory response induced by T. nattereri venom, we treated mice with anti-IL-5 and anti-IL-17A before the immunization and rechallenge. The treatment with both neutralizing antibodies was not able to reverse the splenomegaly and germinal centers formation induced by venom, but regulation of B220 expression on ASC was evident: both antibodies reduced the number of ASC B220neg induced by venom. Our data suggest an important role for IL-5 and IL17A on the development and maintenance of B220neg ASC and B1a population, contributing to maintenance of long-term protective immunity by the venom. Support: FAPESP.