FERNANDEZ Pablo Mariano
congresos y reuniones científicas
The tumor antigen NGcGM3 is a human CD1d ligand capable of mediating B cell and NKT interaction
GENTILINI, M.V.; PEREZ, M.E.; FERNANDEZ, P.; FAINBOIM, L.; ARANA, E.
Congreso; International Congress of Immunology 2016; 2016
The ganglioside NGcGM3 is a tumor antigen (Ag). Some people have circulating Ag specific IgGs,capable of complement mediated cytotoxicity against NGcGM3 positive cells, relevant for tumorsurveillance. Considering the Ag's chemical nature, w e postulated it as a candidate ligand for CD1d.We aimed to assess w hether the immune mechanism involved in the generation of anti-NGcGM3 Absentailed an interaction betw een B cells (Bc) and invariant NKT cells (iNKT).We set up a cell free Ag presentation assay using a recombinant CD1d-IgG1 fusion on NGcGM3-coated plates and tested w hether there w ere differences in the binding of the fusion and an IgG1isotype control. Differences betw een them w ere reproducibly significant (p< 0.01), w hich w as alsotrue for differences w ith uncoated control w ells. The results w ere confirmed through alternativebiochemical assays including competitive ELISA w ith a know n CD1d ligand (IC50 1.2 mmol/L). UsingFACS, w e demonstrated that human Bc present NGcGM3 in a CD1d context and paraformaldehydetreatment of cells expressing CD1d affects the presentation. Finally, by co-culturing primary humanBc w ith autologous iNKT and measuring Ki-67 expression, w e detected a significant increment in theproliferation of both cell populations w hen Ag w as on the medium, w hich w as abrogated by blockingCD1d.Our findings identify a novel, endogenous, human CD1d ligand, w hich is sufficiently competent tostimulate iNKT. We postulate that CD1d-restricted Bc presentation of NGcGM3 drives effective iNKTactivation, a mechanism involved in the antitumor response that has not been previously describedfor humans, w hich may contribute to understanding anti-NGcGM3 occurrence