Fig. 1.

Effect of immune cell depletion on lung tumour development in A/J mice induced with NNK. Depletion of CD4⁺ or CD8⁺ T cells, macrophages, neutrophiles and NK cells was initiated in 6-week-old A/J mice using i.p. injections with 100 μg of anti-CD4, anti-CD8, anti-CD11b or anti-Gr-1 mAb or 300 μg of anti-asialo GM1 ab, respectively. Two days after first application of depleting antibodies, mice were induced for lung cancer with 2 mg of NNK. Treatment with antibodies or control IgG was performed twice a week for 20 weeks. The tumour burden was assessed in a blinded manner. a Tumour number and b tumour volume for mice depleted of CD4⁺ or CD8⁺ T cells, macrophages or neutrophils demonstrated no significant differences compared to saline- or control rat IgG-treated mice. c Depletion of NK cells with anti-asialo GM1 Ab showed an increased tumour number compared to saline-treated mice or mice treated with control rabbit IgG (n = 5; P = 0.047 saline vs anti-asialo GM1 and P = 0.039 rabbit IgG vs anti-asialo GM1, Student’s t test). d Differences in tumour volume of NK cell-depleted mice were not significant compared to control groups. *P < 0.05