Detection of the status of tumour-infiltrating CD4(+) T-cell subpopulations in squamous cell carcinoma of the head and neck (HNSCC) using real-time RT-PCR detection of CD4 mRNA

Several studies have reported tumour infiltrating CD4(+) T cells as a favourable prognostic factor in some types of cancer. We investigated 37 head and neck squamous cell carcinomas (HNSCC) at different stages, using immunohistochemical staining for CD4(+) infiltrates and real-time reverse transcription polymerase chain reaction (RT-PCR) detection of CD4 mRNA. The CD4(+) infiltrates were evaluated and expressed as a percentage according to the ratio of CD4(+) T cells to epithelial cells in the cancer cell nests and to the overall inflammatory cell infiltrate in the tumor stroma. The CD4 mRNA expression level strongly correlated with the CD4(+) infiltration score in the cancer epithelium (r(s) = 0.858, P < 0.001) and in the cancer stroma (r(s) = 0.797, P < 0.001). These results indicate that the real-time RT-PCR assay is a sensitive and reliable method for the detection of CD4 mRNA, and that it could be used to reassess CD4(+) infiltration status in resected specimens from patients with HNSCC.