B-LYMPHOCYTE DYNAMICS IN SMALL INTESTINE DURING TRYPANOSOMA CRUZI INFECTION

GARECA JULIO C; GAZZONI YAMILA; ALMADA LAURA; BRUNOTTO VALENTINA; ACOSTA-RODRÍGUEZ EVA V; MONTES CAROLINA L; GRUPPI ADRIANA

La Plata

Congreso; REUNIÓN CONJUNTA SAIC SAI&FAIC SAFIS 2022; 2022

The acute phase of experimental Trypanosoma cruzi infection re-sults in splenomegaly and expansion in lymph nodes. T. cruzi in-fected mice exhibit polyclonal B cell activation, hypergammaglobu-linemia and unspecific antibodies (Abs) in sera. On the other hand,parasite-specific IgG isotypes are also present in the infected miceand have been described as an important mechanism to controlparasitemia. The contribution of the different B cells subpopulationsfrom the secondary lymphoid organs to this infection are diverse andnot completely understood. In this work, we proposed to evaluatethe gut response during T. cruzi infection since intestine is the tissuewith the highest number of B cells. For that, 8-12 weeks old C57BL/6mice were intraperitoneally injected with 5000 trypomastigotes of T.cruzi Tulahuén strain or with PBS (control mice). At different dayspost infection (dpi) small intestine, Peyer’s patches (PP) and mesen-teric lymph node were obtained. By macroscope evaluation we ob-served a decrease in the number and size of PP at the time of high-est parasitemia (18 dpi). This decrease in PP was transient since at82 dpi PP recovered the normal size. By immunofluorescence (IF),at 18 dpi, we observed a decrease in B and CD4+ and CD8+T cellsin PP and infiltrating T cells in the muscle layer of ileum sections.Accordingly, by FACS, we observed that PP had a marked decreasein the number of T and B cells, being the greatest reduction in B cellpopulation. IF of mesenteric lymph nodes of infected mice showedthat CD169+ metallophilic macrophages disappeared from the sub-capsular sinus and clustered around the follicles. On the other hand,follicles were disorganized and infiltrated by CD4+ T cells. Based onthe results we hypothesize that the small intestine could be contrib-uting lymphocytes to secondary lymph nodes.