Quantification of radiolabelled granulocyte migration in vivo

Quantification of the tissue localisation of granulocytes is difficult, particularly in man. With the aim of facilitating such quantification, a technique is described which combines the micropore filter skin window technique with the infusion of autologous 111In-labelled granulocytes. The radioactivity in the removable micropore filters, placed on small forearm skin window abrasions, was compared with peripheral blood radioactivity following injection of 111In-labelled 'pure' granulocytes in normal subjects. Radioactivity in filters from abrasions which were made 8 h or more before injection of labelled cells followed the same time course as the cell-associated radioactivity in whole blood, but radioactivity in filters from abrasions made nearer to the time of labelled granulocyte injection increased to reach a peak 3-8 h after cell injection, at a time when cell-associated blood radioactivity had fallen to about 50% of its initial value. Exercise appeared to induce a transient decrease in radiolabelled granulocyte migration into the filters. This technique offers a means of studying the kinetics of granulocyte migration in vivo.