No alteration in NK function or zeta chain expression in NK and T cells of cervical cancer patients

Lung carcinomas do not induce T-cell apoptosis via the Fas/Fas ligand pathway but down-regulate CD3 epsilon expression

BACKGROUND

Non-small cell lung carcinoma (NSCLC) patients have impaired cellular immune responses. It has been hypothesized that tumor cells expressing Fas Ligand (FasL) induce in T lymphocytes: (a) apoptosis (tumor counterattack) and (b) down-regulation of CD3zeta expression. However, the hypothesis of tumor counterattack is still controversial.

METHODS

We analyzed FasL expression on NSCLC cell lines and on tumor cells from lung adenocarcinoma patients by flow cytometry and immunocytochemistry. FasL mRNA expression was detected in NSCLC cell lines using RT-PCR, and functional FasL was evaluated on Fas-expressing Jurkat T-cells by annexin-V-FITC staining and by SubG(1) peak detection. Also, the proapoptotic effect of microvesicles released from NSCLC cell lines in Jurkat T-cells was studied. Alterations in the expression levels of CD3zeta, CD3epsilon, and CD28 [measured as mean fluorescence intensity (MFI)] were determined in Jurkat T-cells after co-culture with NSCLC cell lines or tumor-derived microvesicles. Furthermore, the expression levels of CD3zeta and CD3epsilon in CD4+T and CD8+T lymphocytes from lung adenocarcinoma patients was studied.

RESULTS

Our results indicate that NSCLC cells neither FasL expressed nor induced apoptosis in Jurkat T-cells. Tumor-derived microvesicles did not induce apoptosis in Jurkat T-cells. In contrast, NSCLC cell lines down-regulated CD3epsilon but not CD3zeta chain expression in Jurkat T-cells; this effect was induced by soluble factors but not by microvesicles. In lung adenocarcinoma patients, significant decreases of MFI values for CD3epsilon, but not CD3zeta, were found in CD4+T and CD8+T cells from pleural effusion compared to peripheral blood and in peripheral blood of patients compared to healthy donors.

CONCLUSIONS

Our data do not support the tumor counterattack hypothesis for NSCLC. Nonetheless, down-regulation of CD3epsilon in T-cells induced by NSCLC cells might lead to T-cell dysfunction.

Recent developments in human papillomavirus vaccines

The association of certain high-risk human papillomaviruses with the development of anogenital cancer in humans is well-established. Numerous preclinical studies have underwritten the development of both prophylactic and therapeutic vaccine candidates for clinical evaluation. Prophylactic strategies are utilising virus-like particles composed of the L1 viral capsid protein to induce neutralising antibodies while therapeutic approaches are aimed at generating specific T cells targeted at the viral E6 and/or E7 oncogene products. Thus far, human papillomavirus virus-like particle vaccines have proven to be clinically efficacious in the early trials looking at the prevention of infection. Important future milestones will be showing the prevention of high-grade cervical intraepithelial neoplasia and sufficient longevity for such protection. Different types of therapeutic vaccines including peptide, protein, DNA or viral vector-based vaccines have proven to be safe and immunogenic in patients, although there is often no correlation with clinical outcome. The possibility of combined prophylactic and therapeutic vaccines may offer the best chance for a significant reduction in the incidence of death from cervical cancer worldwide.