The present invention generally relates to a new approach for the therapy of allergic responses, based on targeted
elimination of cells expressing the FcεRI
receptor by a chimeric cytotoxin Fc2′-3-PE40. A sequence encoding amino acids 301-437 of the Fc region of the mouse IgE molecule was genetically fused to PE40—a truncated form of PE lacking the
cell binding domain. The chimeric
protein, produced in E. coli, specifically and efficiently kills mouse
mast cell lines expressing the FcεRI
receptor, as well as primary mast cells derived from
bone marrow. The present invention provides a chimeric
protein for targeted
elimination of FcεRI expressing cells especially useful for the therapy of allergic responses. The said chimeric
protein is comprised of a
cell targeting
moiety for FcεRI expressing cells and a
cell killing
moiety. The preferred killing
moiety is the bacterial
toxin Pseudomonas exotoxin (PE). This
Pseudomonas exotoxin is a product of
Pseudomonas aeruginosa. The present invention also relates to a method for the preparation of said protein. This chimeric protein is prepared by genetically fusing the Fc region of the mouse IgE molecule to PE40, a truncated form of PE lacking the
cell binding domain. The present invention also provides pharmaceutical compositions, for the treatment of allergic diseases and for the treatment of hyperplasias and malignancies, comprising as an
active ingredient the above mentioned chimeric protein and a conventional
adjuvant product.