Histamine-coated particles generate Superoxide (O⁻₂) and chemiluminescence in alveolar macrophages

Abstract

WE have recently shown that histamine bound to red cells forms ‘rosettes’ with various guinea pig leukocytes and that these ‘histamine receptors’ are particularly well expressed on the alveolar macrophage¹. As the lung is a major site of histamine storage and high concentrations of histamine are present in the sputum in certain respiratory diseases such as chronic bronchitis and asthma^2,3, we have performed experiments to determine whether free histamine, or histamine bound to particles, interacts with its membrane receptor to initiate the respiratory burst in alveolar macrophages. Activation of the respiratory burst in phagocytic cells is achieved by a number of agents, both soluble and particulate, many of which bind to the plasma membrane (for example, particles opsonised with complement⁴) through cell surface receptors. This suggests that there may be a close association between ‘membrane recognition’ of certain exogenous stimuli and the enzyme which initiates the primary oxygen-consuming reaction (also thought to be membrane bound and probably ‘NADPH oxidase’⁵). In the experiments reported here Superoxide anion formation (O⁻₂) and chemiluminescence have been measured as these are recognised features of the respiratory burst of phagocytic cells⁵.