Human fibrinopeptide A mediates allergic reaction in mice in the acute phase.

We detected a human humoral peptide that deglycosylates mouse antibody IgE, and found that this peptide had the amino acid sequence ADSGEGDFLAEGGGV. The peptide synthesized according to the sequence also deglycosylated the antibody IgE. The deglycosylated IgE did not induce mouse systemic anaphylaxis. Human fibrinopeptide A has the amino acid sequence indicated above, and a polypeptide extracted from human urine showed an antiallergic effect on humans and mice, which strongly suggests that fibrinopeptide A mediates allergic reaction via antibody IgE-deglycosylation, and is excreted as a polypeptide in urine.