For example, allergen-specific IgG antibodies rather than IgE antibodies were detected in individuals who manifested systemic anaphylaxis against medical reagents, such as protamine, dextran and recombinant IgG, including anti-tumour necrosis factor-α (Kraft et al, 1982; Weiss et al, 1989; Adourian et al, 1993; Cheifetz et al, 2003). Here, IGHE is linked to anaphylaxis.