High number of tumour-infiltrating lymphocytes is associated with apoptosis in non-small cell lung carcinoma
Aim: To test whether the number of tumour-infiltrating mononuclear cells (MNC), namely T-lymphocytes (TIL) and, to a lesser degree, B-lymphocytes and macrophages, is associated with tumour cell apoptosis in non-small cell lung carcinoma (NSCLC). Methods and results: Eighty-four non-small cell lung tumours were analysed with specific antibodies and the extent of apoptosis was determined using 3′-end labelling of fragmented DNA (TUNEL). All parameters were determined from the same tumour areas. In general, adenocarcinomas showed a higher number of MNC than squamous cell carcinomas (p=0.04). The number of MNC increased concurrently with the grade of tumour, occurrence being highest in high grade (III) tumours (p=0.05). The number of apoptotic cells was significantly higher in tumours with a high number of CD3+ and CD8+ lymphocytes (p=0.01) and B-cells (p=0.05). Tumours showing abnormal p53 protein expression had a significantly lower count of CD8+ T-cells compared to p53-negative tumours (p=0.03). Conclusions: Our results showed an association between lymphocytic infiltration and extent of apoptosis in NSCLC, suggesting that an attempt to suppress the growth of transformed tumour cells exists even when the tumour has reached an advanced stage.
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