CIBICI   14215
CENTRO DE INVESTIGACION EN BIOQUIMICA CLINICA E INMUNOLOGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Marginal zone B cell expresses higher levels of PD-L1 than follicular B cells.
Autor/es:
FIOCCA VERNENGO F; BECCARIA CG; GOROSITO SERRÁN M; ACOSTA RODRIGUEZ EV; MONTES CL; GRUPPI A
Reunión:
Congreso; LVII Reunión Anual de la Sociedad Argentina de Inmunología; 2014
Resumen:
Protective immune responses require specific and balanced
responses to clear pathogens and tumors and yet maintaining
tolerance to self-antigens. Induction and maintenance of T cell
tolerance is achieved by pathways triggered by different pairs of
receptors and ligands. Among them, PD-1 (programmed death-1)
and its ligands PD-L1 and PD-L2 can limit effector T cell responses
preventing immune-mediated tissue damage. The general
aim of our work is to evaluate the PD-1-PD-L1 pathway on B cell
immunity. We first analyzed the expression of PD-1, PD-L1 and
PD-L2 on different B cell subsets. All follicular (FO) and marginal
zone (MZ) B cells expressed similar levels of PD-1 (MFI 8.4±0.3
and 9.6±0.5 respectively) and few MZ and FO B cells expressed
PD-L2 (1.3% and 3.9% respectively p=0.0036). Interestingly, all
MZ B cells expressed PD-L1 and its expression was significant
higher than on FO B cells (p=0.0019). By immunofluorescence,
we observed a B220hiPD-L1hi population in the marginal zone
of spleen sections of C57BL6 mice. Stimuli like LPS, CpG and
tripomastigotes of Trypanosoma cruzi considerably increased the
expression of PD-L1 on B cells. The high expression of PD-L1
by MZ B cells correlates with high production of IL-6 and IL-10
since MZ B cells produce higher concentrations of IL-6 and IL-10
in basal condition and after LPS stimulation, in comparison to FO
B cells. PD-L1 and PD-L2 can signal bi-directionally by engaging
PD-1 on T cells which can deliver signals into PD-L1/2-expressing
cells. Thus, MZ B cells could regulate immunity or be regulated
via PD-1/PD-L1 pathway, particularly upon activation during an
infectious process. Functional studies are currently being performed
in our laboratory.