Accumulation of adoptively transferred adherent, lymphokine-activated killer cells in murine metastases

While close contact between lymphokine-activated killer (LAK)/adherent, lymphokine-activated killer (A-LAK) cells and tumor cells is believed to be a prerequisite for initiating the events leading to tumor cell lysis, clear evidence for the ability of these effector cells to infiltrate tumors or tumor metastases in vivo still has to be obtained. In the present study, we report that a significant fraction of adoptively transferred A-LAK cells, labeled with fluorochromes for identification, accumulates in lung and liver metastases of the B16 melanoma, the MCA 102 sarcoma and the Lewis lung carcinoma lines. Thus, 5- to 10-fold higher numbers of A-LAK cells were found in the malignant lesions compared to the surrounding normal tissue. The infiltration seemed very heterogeneous after intravenous injection of moderate numbers of A-LAK cells (15 x 10(6)). However, after adoptive transfer of 45 million A-LAK cells, an A-LAK cell/tumor cell ratio higher than 1:1 in most metastases was observed. Surprisingly, approximately 5% of the lung metastases seemed totally resistant to infiltration even though neighboring metastases were highly infiltrated. While substantial infiltration of lung metastases was seen after i.v. injection, significant infiltration of liver metastases was seen only after intraportal injection of the A-LAK cells indicating impaired traffic of intravenous injected A-LAK cells through the lung capillaries. These results present direct evidence that A-LAK cells, upon a proper route of administration, have the potential to migrate to and heavily infiltrate metastases from murine tumors of different origin.