Methods for desensitization of a mammal suffering from IgE mediated allergy comprise the steps of: administering to said mammal a therapeutically effective amount of an immunogenic and hypoallergenic composition which comprises (i) a Phl p 6 molecule having an N-terminal truncation which makes the molecule at least lack IgE binding capacity, and/or (ii) a Phl p 6 molecule having a C-terminal truncation which makes the molecule at least lack IgE binding capacity, wherein the molecules of (i) and (ii), if employed in combination, together span the complete sequence of Phl p 6, and a pharmaceutically acceptable carrier.