The Proposed Use of H-Receptor Antagonists in Urticaria and Atopic Dermatitis

To the Editor.—  Over the past few years, it has been learned that H₂-receptor sites exist on peripheral vascular walls and on the surface of lymphocytes (possibly polymorphonuclear leukocytes and macrophages as well). Grennan et al demonstrated effective H₂-receptor blockade of xenon clearance from histamine-treated canine diarthrodial joints, a model providing indirect measure of synovial perfusion.¹ Fermont et al found in human skin that pyrilamine (an H₁-antagonist) and metiamide (an H₂-antagonist) provided significantly greater suppression of histamineinduced flares than mepyramine alone.²Histamine uptake by tuberculinsensitized lymphocytes could be blocked by metiamide, suggesting H₂-receptor sites on these cells.³ Histamine inhibition of T-lymphocyte mediated functions could be effectively blocked with H₂-antagonists.⁴ Cimetidine enhancement of delayed hypersensitivity responses in skin has been shown.⁵Based on the above data, H₂-antagonists may be expected to have