Enhanced expression of IFN-γ mRNA in CD4+ or CD8+ tumour-infiltrating lymphocytes compared to peripheral lymphocytes in patients with renal cell cancer

The mRNA expression of the cytokines IFN-γ, IL-10 and TNF-α and the proapoptotic factor Fas ligand (FasL) was compared in freshly isolated CD4 + and CD8 + tumour-infiltrating lymphocytes (TIL) and simultaneously obtained autologous CD4 + and CD8 + peripheral blood lymphocytes (PBL) from 20 patients with renal cell carcinomas (RCC). TIL were isolated from mechanically disaggregated tumour material and PBL from peripheral blood by gradient centrifugation. The cells of the interphase were depleted from tumour cells with anti-human epithelial antigen magnetic beads and then positive selection was performed with anti-CD4 or anti-CD8 magnetic beads. In these pure lymphocyte preparations the constitutive expression of cytokine and FasL mRNAs was determined by using a PCR-assisted mRNA amplification assay. In the CD4 + TIL from the 20 patients with RCC, levels of mRNAs encoding for IFN-γ ( P ≤ 0.001), IL-10 ( P ≤ 0.05), and FasL ( P ≤ 0.001) were significantly higher than in the autologous CD4 + PBL. Comparison of CD8 + TIL and CD8 + PBL revealed a significant higher expression of IFN-γ ( P ≤ 0.001), IL-10 ( P ≤ 0.01) and FasL mRNAs ( P ≤ 0.001) in the former. However, TNF-α mRNA levels were significantly lower in the CD8 + TIL than in the CD8 + PBL ( P ≤ 0.05). These data reflect a general in vivo activation of RCC infiltrating lymphocytes in the tumour surrounding. © 2000 Cancer Research Campaign