Effect of different T. cruzi stages in antigen presenting cells in vitro and in vivo.

ESTELA LAMEL; CAROLINA PONCINI; BRENDA CELESTE GUTIÉRREZ; STELLA M GONZÁLEZ CAPPA; MARCEL RAMIREZ

Mar de Plata

Encuentro; LXIV Reunión Anual de la Sociedad Argentina de Inmunología. Reunión conjunta SAIC-SAI-SAFE; 2016

Previous studies demonstrated that trypomastigotes (Tp) purified from blood regulate the activation and functionality of bone-marrow derived (BM) dendritic cells (DCs). In addition, in vivo we described the tolerogenic properties of myeloid DCs in the experimental model of infection with a highly virulent strain inoculated intradermally (Poncini 2008 and 2015). Naturally-occurring, the infection occurs when metacyclic (m)Tp reach mucosa or the feeding wound. Here, we analysed the effect of blood (b)Tp or mTp in BMDCs or in DC-cell line XS106(Mohan 2005) in vitro and the effect of both parasite stages in vivo.By flow cytometry, we observed that XS106 cell-line presented basal activation with intermediate tohigh expression of CD86, CD40 and MHCII markers that are not affected by Tp (p˃0,05). In addition, basal production of IL-10 was detected in the presence or absence of Tp that is downregulated by LPS (p˂0,05).Regarding cell infection, bTp were able to multiply inside both BMDCs and XS106. However, parasite cell circle was aberrant in XS106 DCs. On the contrary, mTp differentiated in vitro displayed low capacity to infect both BM and XS106 DCs.The intradermal infection with bTp and mTp showed slight differences in relation to cell recruitment into skin at 3 and 7 days post-injection. However when mice were infected with mTp, no circulating parasites were detected during 50 days ofscreening. When animals inoculated or not (controls) with mTp were challengedwith bTp, only mTp-injected showed low parasitemia and 100% of survival versus100% of mortality in the other group. Analysis of splenic cell populationsdemonstrated enhanced activation in antigen presenting cells in mTp injected animals versus controls.These results suggest that bTp and mTp triggers different immune responses at the very beginning of the infection.