A composition comprising six contiguous overlapping peptides, wherein - the first peptide consists of the sequence from amino acid T99 to amino acid G168 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the second peptide consists of the sequence from amino acid A164 to amino acid S200 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the third peptide consists of the sequence from amino acid R193 to amino acid E227 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the fourth peptide consists of the sequence from amino acidP220 to amino acid R254 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the fifth peptide consists of the sequence from amino acid R249 to amino acid D282 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, and - the sixth peptide consists of the sequence from amino acid A278 to amino acid L320 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained. - the first peptide consists of the sequence from amino acid T99 to amino acid G168 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the second peptide consists of the sequence from amino acid A164 to amino acid S200 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the third peptide consists of the sequence from amino acid R193 to amino acid E227 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the fourth peptide consists of the sequence from amino acidP220 to amino acid R254 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, - the fifth peptide consists of the sequence from amino acid R249 to amino acid D282 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained, and - the sixth peptide consists of the sequence from amino acid A278 to amino acid L320 of a polypeptide having SEQ ID NO:27 wherein the reactivity of said peptide to IgE antibodies of subjects who are allergic to house dust mites is eliminated while the reactivity with the T lymphocytes from subjects who are allergic to house dust mites is retained.