A method for following human lymphocyte traffic using indium-111 oxine labelling.

A method is described whereby large numbers of human lymphocytes are separated from peripheral blood and labelled in vitro with indium-111 oxine. Following autologous reinjection, the distribution within the body is followed by means of serial blood samples, surface-probe counting and gamma camera imaging. The distribution of radioactivity following reinjection of heat-damaged labelled lymphocytes and free indium-111 oxine is different from that of 'normal' lymphocytes. The results suggest that the separation and labelling procedure does not cause significant physical damage to the lymphocytes The importance of restricting the specific lymphocyte activity to 20-40 microCi per 10(8) cells in order to minimize radiation damage to the lymphocytes is emphasized. Good resolution of lymphoid structures is obtained using gamma camera imaging and the changes recorded in organ distribution correlate well with data from animal models of lymphocyte migration. Thus, indium-111 oxine labelling of human lymphocytes provides a non-invasive method whereby the migratory properties of human lymphocytes can be followed.