In vivo distribution and tissue localization of highly purified rat lymphokine-activated killer (LAK) cells

Abstract

A highly purified population of effector lymphokine-activated killer (LAK) cells was generated by culturing nylon-wool column nonadherent rat splenocytes in the presence of interleukin 2 (IL-2), and the cells which became adherent to the plastic flasks were separated and maintained in culture for a total of 5 days. More than 95% of these cells had the morphology of large granular lymphocytes (LGL), expressed surface phenotypes characteristic of rat natural killer (NK) cells, and were able to kill NK-sensitive and NK-resistant tumor target cells. 51Cr-labeled purified A-LAK cells injected intravenously into syngeneic F344 rats localized primarily in the lungs 2 hr after injection but then redistributed to the liver and the spleen by 24 hr after injection. The effects of various immunological manipulations on the distribution pattern of the isolated LAK cells were evaluated. Treatment of the host with 500 rad total body X-irradiation 24 hr before cell injection resulted in an early uptake of LAK cells into the liver and the spleen, whereas treatment with cyclophosphamide 1 day before cell injection, resulted in an early uptake of LAK cells into the liver but not into the spleen. Treatment of the recipient rats with up to 120,000 units recombinant interleukin-2 intraperitoneally did not result in the accumulation of LAK cells at the site of IL-2 injection, nor did it result in a modulation of the overall distribution pattern or total recovery of radiolabeled LAK cells. Rather, the administration of IL-2 was necessary to maintain the cytotoxic activity of the injected LAK cells isolated from the liver and spleen.