The invention relates to microparticules fonctionalized with alphagalactosylceramide for sustained iNKT cell activation. Delivering of alphagalactosylceramide (a natural iNKT agonist presented by DC to iNKT cells) through functionalized microparticules allows to prevent the iNKT anergy observed with non vectorized alphagalactosylceramide. Such approach reopens the doors of the use of alphagalactosylceramide in the treatment of cancer, more particularly the treatment of lung cancer for which alphagalactosylceramide had shown promising short term efficacy.