Granulocyte/macrophage-colony-stimulating factor augments lymphokine-activated killer activity from lymphocytes via...

Therapies with granulocyte/macrophage-colony-stimulating factor (GM-CSF) and interleukin(IL)-2 are designed to activate macrophages and lymphocytes. We investigated whether combined treatment with GM-CSF and IL-2 induced macrophage-mediated antitumor activity and/or T-cell-mediated antitumor activity in lung cancer patients.

Macrophages in the pleural cavity (PCM), lymphocytes in the pleural cavity (PLY), and peripheral blood lymphocytes (PBL) were separated from 48 patients with resectable lung cancer. Lymphokine-activated killer (LAK) activity was assayed by measuring 51Cr release. The proportion of PCM positive for the GM-CSF receptor (GM-CFSR) alpha chain was examined by flow-cytometric analysis and the expression of GM-CSFR alpha chain mRNA in PCM was examined by reverse transcription/polymerase chain reaction analysis.

Treatment with GM-CSF developed no significant antitumor activity in PCM, PLY, or PBL. LAK activity was developed by PLY and PBL after incubation with IL-2. Stimulation with GM-CSF augmented LAK activities in PLY and PBL significantly, when these cells were cultured with autologous PCM (P < 0.05, P < 0.01). Moreover, GM-CSFR-alpha-chain-positive PCM had a higher potential to augmented LAK activities in PLY and PBL than had GM-CSFR-alpha-chain-negative PCM.

These findings suggest that GM-CSF may stimulate GM-CSFR-alpha-chain-positive PCM and that these PCM may augment LAK activities developed by PLY and PBL. Combined treatment with GM-CSF and IL-2, therefore, may be a reasonable approach to treating lung cancer patients.