There are provided peptides derived from antibodies with reactivity against aGPI linkage epitope and functionally-equivalent ligands. These peptides can beused in the therapy and diagnosis of a variety of diseases, all of which areconsidered to be caused by the inappropriate presence in the body ofautoantibodies which are reactive with GPI linkage epitopes. There is alsodescribed a mechanism of action of these autoantibodies which compromises theorganism, so causing disease, and a method of prevention of disease anddetection of the autoantibody.
