mptoms in healthy volunteers after oral provocation with liquid histamine. Allergy Asthma Proc 2004;25:305-11. Medline 16. Pollock I, Murdoch RD, Lessof MH. Plasma histamine and clinical tolerance to infused histamine in normal, atopic and urticarial subjects. Agents Actions 1991;32:359-65. 17.0 Schmi