Tumor antigen-specific CTL and expression of cytokines are detected in the lungs of SCID mice bearing autologous lung tumor. Mice were injected with 5 × 105 tumor cells intravenously. On day 5, after tumor foci were established in the lungs, 5 × 106 CTLs were injected intravenously. On day 10, mice were sacrificed and lung and liver were excised for immunohistochemical and PCR analysis. A, B, C and D. IHC analysis of lungs for the presence of CD8 positive CTLs. Lungs from mice injected with A. tumor cells + tumor antigen-specific CTLs B. tumor cells only, C. tumor cells + influenza nucleoprotein antigen-specific CTL or D. tumor antigen-specific CTL alone. Original magnification: ×200, brown staining shows CD8 positive T cells. E, F and G. RT-PCR analysis. Primers used are specific for human E. CD8, F. IFN-γ and G. β-actin. Lane 1, 100 bp DNA ladder; lane 2, cDNA from lung of SCID mice bearing human tumor only; lane 3, cDNA from liver of SCID mice bearing with tumor only; lane 4, cDNA from lung of SCID mice bearing human tumor and CTLs; lane 5, cDNA from liver of SCID mice bearing tumor and CTLs.