Five leucocyte labelling techniques: a comparative in-vitro study

During the past years, several authors have used labelled leucocytes to detect inflammatory foci. However, before routine use in man. It is necessary to control the viability of labelled cells. Five leucocyte labelling techniques (111In-oxine, 111In-oxine without extraction, 99mTc oxine, pyrophosphate 99mTc, 51Cr) were compared using the same separation methods, conservation medium, viability assays and migration studies. Electron microscopic studies allowed the assessment of cellular damage induced by the labelling techniques as well as the calculation of the percentage of cells disrupted during preparation. Results obtained in vitro using 111In-oxine were not satisfactory and in fact appeared contradictory to those published by the authors using this technique in vivo. Even the best method, pyrophosphate 99mTc labelling, was not completely atoxic, but the functional behaviour of the leucocytes did not seem affected. While in vitro studies offer much information concerning labelled cells, they cannot predict the in vivo behaviour of these cells.