Lymphocytes infiltrating normal human lung and lung carcinomas rarely express gamma delta T cell antigen receptors

It has been suggested that T lymphocytes expressing gamma delta T cell receptors (TCR) could play an important role in the defence of epithelia against infection and neoplastic transformation, but the potential for gamma delta T lymphocytes to serve these functions in human respiratory epithelium has received little attention. In this study, we used immunohistochemical techniques and specific monoclonal antibodies to characterize the number and distribution of T lymphocytes expressing alpha beta and gamma delta TCR in normal human lung and in lung carcinomas. T lymphocytes present in normal bronchi and alveolar parenchyma were predominantly of the alpha beta TCR phenotype, whereas gamma delta T lymphocytes represented only 1.1 +/- 0.7% and 1.3 +/- 0.5% of total CD3+ lymphocytes respectively. An important lymphocytic infiltration was noted in the stroma of all primary lung carcinomas examined, and some T lymphocytes were also present infiltrating between tumour cells. These T lymphocytes were almost entirely alpha beta T cells and only rare gamma delta T cells were found, regardless of the histologic type of carcinoma (0.8 +/- 0.1% of CD3+ T cells). This study demonstrates that T cells present in normal bronchi and lung parenchyma and those infiltrating primary lung carcinomas express predominantly alpha beta TCR. These findings do not support the conclusion that gamma delta T lymphocytes play an important role either in the defence of human lung epithelia or in immune responses directed against primary lung carcinomas.