IMMUNOMODULATORY MECHANISM OF GALECTIN-8 IN THE ADAPTIVE RESPONSE

PRATO CECILIA A.; CARABELLI JULIETA; CAMPETELLA OSCAR; TRIBULATTI MARIA V.

BUENOS AIRES

Congreso; LXV Reunión Anual Argentina de Inmunología; 2017

Galectin-8 (Gal-8) is a mammalian lectin endowed with pro-inflammatory properties. We have previously demonstrated Gal-8 capacity to enhance antigenspecific immune response both in vitro and in vivo, by activating dendritic cells (DCs), and postulated its use as an immuno-stimulatory molecule in vaccine formulations. Here, we studied whether Gal-8 is also involved in antigen internalization and processing by DCs. Firstly, we determined by confocal microscopy that recombinant Alexa488-Gal-8 was internalized by bone marrow-derived dendritic cells (BMDCs) from BALB/cJ mice, co-localizing with EEA-1, an early endosome marker. Remarkably, Gal-8 co-localized with OVA, confirming that Gal-8 is internalized together with the antigen, following the same endocytic pathway. Next, we evaluated the effect of Gal-8 on antigen uptake and processing, using Alexa488-OVA and DQ-OVA (a fluorogenic substrate for proteases) respectively, followed by flow cytometry analysis. We observed that simultaneous addition of Gal-8 and antigen, significantly increased its uptake and degradation by BMDCs. Finally, in order to determine whether the increment in antigen uptake and processing resulted in an enhanced antigen presentation toT CD4+ cells, BMDCs from BALB/cJ mice, previously pulsed with OVA or OVA plus Gal-8, were co-incubated with T CD4+ cells purified from DO11.10TCROVA mouse splenocytes. Notably, a significant increment of T cell proliferation and IFN-g production were observed in the presence of Gal-8.