ABSTRACT
Adoptive immunotherapy with interleukin 2 (IL-2) and lymphokine activated killer (LAK) cells or plastic adherence-enriched LAK cells has produced dramatic reductions in the number of metastatic lesions in several animal systems. In clinical settings, LAK cell therapy has also been successful, with complete or partial responses in 20–30% of the patients with advanced cancer, especially malignant melanoma and renal cell carcinoma. If the anti-neoplastic effect of activated killer cells is dependent on direct contact with the tumor cells, the optimal therapeutic environment would exist when high numbers of the most cytotoxic LAK cell type are present in the in the tumor. Injection of LAK cells by the intravenous (i.v.) route results in direct delivery of these cells to the lungs and lung metastases since all i.v. injected cells initially reach the lungs. In order to infiltrate liver metastases, LAK cells must first traverse the lung vasculature and the capillary bed of the intestinal tract.
