ANALYSIS OF CELLS INVOLVED IN GERMINAL CENTER REACTION DURING Trypanosoma cruzi INFECTION

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

San Miguel de Tucumán

Congreso; LXVII Reunión Anual de la Sociedad Argentina de Inmunología; 2019

Germinal Centers (GCs) are micro-anatomical structures that emerge within secondary lymphoid organs in response to T cell-dependent antigens. Within GCs, B cells can differentiate into antibody-secreting cells (ASC) and memory B cells. Follicular helper T cells (Tfh) are instrumental in supporting Antibody (Ab) affinity maturation and humoral memory. Other GC protagonists are follicular cytotoxic T cells (Tfc) whose function is not well established. We aimed to study the response of the different cell subsets involved in GC reaction during T. cruzi infection. For that, C57BL/6 mice were intraperitoneally infected with 5.000 trypomastigotes (Tulahuén strain); and the frequency and number of the different populations in the spleen and lymph nodes were evaluated by flow cytometry at different days post infection. Mice injected with PBS were evaluated as controls. We observed that the peak of Tfh (CD4+CD8-B220-CXCR5+ICOS+PD-1+), Tfc (CD8+CD4-B220-CXCR5+PD-1+ICOS+) and ASC (B220loCD138+) response preceded the peak of GCs-B cells (B220+FAS+GL-7+Bcl-6+). Additionally, considering that IL-17A is a regulator of B cell trafficking in the GC and its biological effect is mediated by IL-17RA we also evaluated the expression of this receptor on CG-B cells, Tfh and Tfc. We observed that IL-17RA expression was higher in CG-B cells than in other B cell subsets (naïve, follicular and ASC) (p<0,05). Interestingly, Tfc expressed higher levels of IL-17RA than Tfh (p<0,05). These results suggest that IL-17 could signal into GC-B cells to sustain the GC response during T. cruzi infection. Further studies are needed to understand the role of IL-17 and Tfc on the CG response.