CHARACTERIZATION OF EXTRAFOLICULAR PB RESPONSE IN T CRUZI INFECTION

ALMADA LAURA; GAZZONI YAMILA; FIOCCA VERNENGO FACUNDO; BECCARIA CRISTIAN GABRIEL; BOCCARDO SANTIAGO; MONTES CAROLINA LUCÍA; ACOSTA RODRÍGUEZ EVA V.; GRUPPI ADRIANA

San Miguel de Tucumán

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

B cells are the unique population able to differentiate into antibody-secreting-cells (ASC). The Germinal Center reaction-GC- and the extrafolicular-EF- response generate different types of ASC which provide long- and short-term humoral immunity against infections, respectively. The participation of different cell populations, like follicular T helper cells-Tfh-, is key in these processes. A regulatory population of EF-ACS (B220int CD138+ Blimp-1+) characterized by high expression of PD-L1 and CD39 was described by our group recently, in a T cruzi infection model in mice. The EF-ASCs have the capability to modulate the T-cell response in the infection. The aims of our work are to characterize the phenotype of regulatory EF-ASC and the mediators involved in their differentiation. For that, C57BL6 mice were infected with 5000 trypomastigotes of T. cruzi (Tulahuén), and splenic, lymphatic and bone marrow (BM) lymphocytes were evaluated by FACS and Immunofluorescence at different days post infection (dpi). We observed the peak of frequency 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 until day 23pi and this frequency is significantly reduced from day 28pi (p<0.005). Only the 15% of BM-long-lived ASC from chronic phase of infection (130dpi) express high levels of PD-L1 and CD39. Additionally, we found a CXCR5negPD1+ICOS+Bcl-6+CD4+Tcell population in spleen of infected mice. In this context, this CXCR5negTfh-like population could be located in the EF-area and could be interacting with EF-ASC, either collaborating with ASC or being regulated by them.