Human small‐cell lung‐cancer cells are cytokine‐resistant but NK/LAK‐sensitive

We have studied the effects of 8 cytokines and their combinations on the in vitro growth of 10 human small‐cell cancer lines (SCLC). Interferon‐α and γ (IFN‐α and γ) caused significant but slight growth inhibition over a 7‐day incubation period. However, none of the other 6 cytokines, tumor necrosis factor (TNF), lymphotoxin (LT), interleukin‐1β (IL‐1β), interleukin‐2 (IL‐2), transforming growth factor‐β1 (TGF‐β1), or granulocyte colony‐stimulating factor (G‐CSF), modified SCLC cell proliferation. In contrast, all 10 lines were sensitive to lysis by natural killer (NK) and lymphokine‐activated killer (LAK) cells. Sensitivity to LAK cells could be Increased by pretreatment of SCLC cells with IFN‐γ. As resistance to the cytostatic/cytotoxic activity of some cytokines has been associated with autocrine production of cytokines, we screened the SCLC lines for cytokine mRNAs. Within the limits of detection of the assay we found no expression of TNF, TGF‐β1, IL‐1β or IL‐6 mRNA in the 10 SCLC lines.