Analysis of cells involved in germinal center reaction in Trypanosoma cruzi infection

GAZZONI, YAMILA; ACOSTA RODRÍGUEZ, EVA V.; ALMADA, LAURA; GRUPPI, ADRIANA; MONTES, CAROLINA L.

Banff

Congreso; B cell Renaissance: Epigenetics, Regulation and Immunotherapy; 2020

Germinal Centers (GCs) B cells can differentiate into antibody-secreting cells and memory B cells in response to T cell-dependent antigens. Within GCs, follicular helper T cells (Tfh) are crucial for affinity maturation. Other GCs-protagonists are follicular cytotoxic CD8+T cells (Tfc) whose function is not well established. However, it is known that Tfc share Tfh-related molecules.Our aim was to study the response of Tfh and Tfc, the GC reaction and the presence of plasmablast during T. cruzi infection. For this goal, C57BL/6 mice were intraperitoneally infected with 5.000 trypomastigotes (Tulahuén strain) and the frequency and number of the populations mentioned above were evaluated by flow cytometry at different days post infection (dpi) in the spleen and lymph nodes. Mice injected with PBS were used as control group.In the spleen, we observed that the peak of the Tfh (CD4+CXCR5+PD-1+ICOS+), Tfc (CD8+CXCR5+PD-1+ICOS+) and plasmablast (B220loCD138+) response was at 18dpi. In lymph node, the peak of Tfh and plasmablast response was at 23dpi while Tfc, at 18dpi. These responses preceded GC-B cells response (B220+FAS+GL-7+Bcl-6+) which peaked at 28 dpi. Tfc exhibited the higher frequency of cells specific for the immunodominant peptide TSKB20 and higher frequency of CD107a+ and IFN-gamma, TNF-alfa and Granzyme B producing cells than non-Tfc (CD8+CXCR5negPD-1neg) (p