Abstract: Peptide compositions comprising a dimeric peptide which combines two peptide monomers, each independently comprising the amino acid sequence: Asp-X1-X2-Asn-Tyr-Ile-Thr-X3 wherein: X1 is selected from the group consisting of Cys and a Cys derivative; X2 is selected from the group consisting of Cys and a Cys derivative; and X3 is selected from the group consisting of Arg and Glu-Leu-Arg, provided that at least one of X1 and X2 is Cys, whereby a mol percentage of the dimeric peptide in the composition is at least 50 mol percents, or at least 99 mol percents, are disclosed. Further disclosed are processes of preparing such peptide compositions and uses thereof in the treatment of allergic disorders.

Abstract: Peptides corresponding partially to positions 55-64 of the sequence of the complement component peptide C3a are capable of preventing and treating mast cell- and basophil-mediated disorders by inhibiting IgE- or IgG-mediated triggering and/or by inhibiting the Fc?RI- and/or Fc?R-induced secretory response, while obviating the anaphylatoxic response. These peptides are useful for prevention and/or treatment of allergic disorders where mucosal-type and/or serosal-type mast cells and/or basophils are involved such as asthma, allergic dermatosis, and gastrointestinal allergies.

Abstract: Peptides corresponding partially or entirely to positions 50-77 of the sequence of the complement-derived peptide C3a and analogs thereof are capable of inhibiting IgE-mediated triggering and/or the Fc&egr;RI-induced secretory response of mucosal mast cells. These peptides are useful for prevention and/or treatment of allergic disorders caused by IgE mediated (Type I) hypersensitivity where mucosal-type mast cells are involved, such as hay fever, asthma, some cases of urticaria or allergic conjunctivitis.