Histamine H-1 binding site on human polymorphonuclear leukocytes

Neutrophilic polymorphonuclear leukocytes (PMN) infiltrate the sites of allergic reactions and may respond to histamine, one of the major mediators of allergy. In order to characterize histamine interactions with PMN, the binding of [³H]pyrilamine was studied. Human PMNs bind [³H]pyrilamine in a specific, saturable, and reversible fashion and demonstrate specificity (H-1 antagonists > histamine > H-2 antagonists) for the competitive binding agents studied. Human PMNs have a homogeneous population of H-1 receptors of moderate affinity (K_d=52 nM) in large number (265 × 10³/cell) which do not demonstrate cooperativity. Thus PMNs attracted to sites of allergic inflammation have H-1 binding sites which may respond to histamine stimulation.