Mannosamine-desthiobiotin adduct (compound MDTBA) is a carrier immunogenicity-reducing hapten that reduces the immunogenicity of protein carriers upon conjugation to available free amines on the carrier protein surface. Conjugation of Mannosamine-desthiobiotin adduct to hsIgG significantly (>1-fold) reduced the immunogenicity of hsIgG. Mannosamine-desthiobiotin adduct can be used in antigen design research.