CHARACTERIZATION OF EXTRAFOLLICULAR PB RESPONSE IN T CRUZI INFECTION

ALMADA, LAURA; GAZZONI, YAMILA; FIOCCA VERNENGO, FACUNDO; BECCARIA, CRISTIAN G.; BOCCARDO, SANTIAGO; MONTES, CAROLINA; ACOSTA RODRIGUEZ, EVA V.; GRUPPI, ADRIANA

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

B cells are the unique popula�on able to differen�ate into an�body-secre�ng-cells(ASC). The Germinal Center reac�on-GC- and the extrafolicular-EF- response generatedifferent types of ASC which provide long- and short-term humoral immunity againstinfec�ons, respec�vely. The par�cipa�on of different cell popula�ons, like follicular Thelper cells-T�-, is key in these processes. A regulatory popula�on of EF-ACS (B220intCD138+ Blimp-1+) characterized by high expression of PD-L1 and CD39 was described byour group recently, in a T cruzi infec�on model in mice. The EF-ASCs have the capabilityto modulate the T-cellresponse in the infec�on. The aims of our work are to characterizethe phenotype of regulatory EF-ASC and the mediators involved in their differen�a�on.For that, C57BL6 mice were infected with 5000 trypomas�gotes of T. cruzi (Tulahuén),and splenic, lympha�c and bone marrow (BM) lymphocytes were evaluated by FACS andImmunofluorescence at different days post infec�on (dpi). We observed the peak offrequency of ASC at 18dpi and the GC (LiB Fas+GL7+) peak at 28dpi, in spleen. The 99%of ASC express high levels of CD39 and PD-L1 un�l day 23pi and this frequency issignificantly reduced from day 28pi (p<0.005). Only the 15% of BM-long-lived ASC fromchronic phase of infec�on (130dpi) express high levels of PD-L1 and CD39. Addi�onally,we found a CXCR5negPD1+ICOS+Bcl-6+CD4+Tcell popula�on in spleen of infected mice.In this context, this CXCR5negT�-like popula�on could be located in the EF-area andcould be interac�ng with EF-ASC, either collabora�ng with ASC or being regulated bythem.