DEVELOPMENT OF A METHOD FOR MONITORING THE MIGRATION OF IN-111-LABELED EOSINOPHILS AND NEUTROPHILS TO THE LUNGS OF ANESTHETIZED GUINEA-PIGSBY GAMMA-SCINTIGRAPHY AND BRONCHOALVEOLAR LAVAGE

A method to introduce In-111-labelled neutrophils or eosinophils into the circulation of anaesthetized, ovalbumin-sensitized guinea pigs and monitor their pulmonary accumulation using gamma scintigraphy has bee n developed, The method is based on the ability to use Tc-99m macroagg regated albumin (MAA) to create a pulmonary perfusion image as a templ ate for the lungs of individual guinea pigs which can be superimposed on to the image produced by the In-111-labelled leukocytes injected in to the same animal, Intravenous injection of the labelled leukocytes w as shown to produce a high density of radioactivity in the heart and l ungs with little circulation to the rest of the body, This suggested a n immediate 'trapping' of leukocytes in the pulmonary vascular bed. A more effective distribution of In-111-labelled cells was achieved by i njecting them into the right carotid artery. This ensured more efficie nt circulation of the cells and resulted in their appearance in the lu ngs, liver and spleen. However, it was found that the contralateral ca rotid artery had to be tied off to prevent the cells only circulating to the superior left quadrant of the animal. Bronchoalveolar lavage of the lungs following i.v. injection of In-111-labelled neutrophils sho wed no significant difference in radioactivity of lavage fluid between guinea pigs challenged 24 h beforehand with inhaled saline or ovalbum in, In contrast, when labelled eosinophils were injected, there was a significantly greater mean radioactivity level in lavage fluid after o valbumin challenge than after saline. In conclusion, gamma scintigraph y provides an accurate measure of the amount of activity from In-111-l abelled leukocytes in the lung region which is specific for each anima l.