Fate of intravenously administered rat lymphokine-activated killer cells labeled with different markers.

Rat lymphokine-activated killer (LAK) cells, generated by adhering rat splenocytes isolated from the 52% Percoll density fraction to plastic flasks, demonstrate restricted in vivo tissue distribution, localizing in the lungs and liver after 2 h, but redistributing into the liver and spleen 24 h after i.v. administration. However, a different pattern of distribution was observed when this population of LAK cells was labeled with one of four commonly used radioisotopes. For example, LAK cells showed a high distribution into the lungs 30 min after administration when labeled with 51Cr, 125I-dUrd or 111In-oxine, whereas 111InCl-labeled LAK cells showed an equal distribution into the blood, lungs and liver at this time. Two hours after administration, cells labeled with 111In-oxine showed an equivalent distribution into the lungs and liver, those labeled with 125I-dUrd or 51Cr showed a high accumulation in the lungs, whereas those labeled with 111In-Cl entered more into the liver and blood. The pattern of distribution of 111In-Cl- or 111In-oxine-labeled cells was confirmed using gamma camera imaging analysis. By 24 h, LAK cells labeled with 111InCl, 111In-oxine or 51Cr distributed in the liver and spleen in variable concentrations. In contrast, cells labeled with 125I-dUrd were not detected in any organ tested. This study was paralleled by monitoring the distribution of LAK cells labeled with Hoechst 33342 (H33342) and analyzed for the presence of fluoresceinated cells in different organs either by flow cytometry analysis, or in frozen section. The data indicate that the distribution pattern of LAK cells labeled with 111In-oxine is the closest to the distribution of H33342-labeled cells. Of all the radioisotopes used, 125I-dUrd has the most disadvantages and is not recommended for monitoring the in vivo distribution of leukocytes.