Heterodimers MHC class II soluble functional stabilized by disulfide bonds

A molecule of recombinant MHC class II, comprising: (i) all or part of the extracellular part of an α chain of MHC class II; (Ii) all or part of the extracellular part of a β chain of MHC class II; wherein (i) and (ii) provide a binding domain functional peptide and wherein (i) and (ii) are linked by a disulfide bond between cysteine ​​residues located in the domain α2 of said α chain and β2 domain of said β chain, wherein said cysteine ​​residues are not present in α2 and β2 MHC class II native domains, and wherein said recombinant molecule does not comprise a leucine zipper motif.