The presence of lymphocytic infiltration in prostate carcinomas has been shown to have prognostic relevance. However, it is not yet clear if this infiltrate represents a tumor-specific activated cell population or not. Therefore, the aim of the present study was to characterize the activation status of freshly isolated tumor infiltrating lymphocytes (TIL) from prostate carcinomas (PCa) and benign hyperplasia (BPH) with respect to the mRNA expression of cytokines and apoptotic factors.
TIL were isolated from mechanically disaggregated tumor material by gradient centrifugation. The cells of the interphase were depleted from epithelial cells with anti-human epithelial antigen magnetic beads and then CD3+- lymphocytes were selected with magnetic beads against this determinant. In these pure lymphocyte preparations the mRNA expression of IL-1, IL-10, IFN-γ, TNF-α, Fas and Fas ligand was determined by using a semiquantitative RT-PCR. Contamination with tumor cells was excluded by a PCR for PSA and PSMA.
The CD3+-TIL from 21 patients with PCa and 20 patients with BPH expressed significantly higher levels of IL-10- and Fas ligand-mRNA compared to the autologous CD3+- PBL, whereas the expression of IL-1-, TNF-α- and Fas-mRNA was not different in either cell population. In contrast, the mRNA levels of IFN-γ were significantly higher only in the CD3+-TIL from the carcinomas but not from the BPH compared to autologous CD3+-PBL.
Since high levels of IFN-γ have been reported to be produced by specifically lytic lymphocytes, our results suggest the presence of specifically activated TIL in the prostate carcinomas but not in the BPH, whereas inflammatory activated TIL are present both in the carcinomas and the BPH. Prostate 45:1–7, 2000. © 2000 Wiley-Liss, Inc.