Differential production of gamma delta T cells in the urine of bladder cancer patients receiving Bacillus Calmette Guerin immunotherapy

Abstract

Bacillus Calmette Guerin (BCG) intravesical therapy of bladder cancer is arguably the most effective immunotherapy for any human solid tumour. It combines a high incidence of remission induction with a low level of side effects and a low rate of recurrence. Its mechanism, however, remains poorly understood. In this study we have investigated whether gamma delta T lymphocytes, which are known to be activated by mycobacteria, are preferentially induced in patients urine following therapy. This has necessitated the development of a procedure which facilitates the preservation, enrichment and detection of small number of lymphocytes [especially of those bearing gamma delta T cell receptor (TCR)I which appear in patients urine. Here we describe in detail a method for phenotyping of a minor subpopulation of lymphocytes in patients' urine, namely, gamma delta T lymphocytes which comprised less than 0.1% of all urinary sells. Using this technique we have found gamma delta T cells in the urine of all patients. Furthermore, the patients could be separated into 2 distinct groups, with low and high numbers of gamma delta cells (0.5-5% and 5-20% respectively of the CD3 positive cells). The elevation of gamma delta T cells was observed locally but not in peripheral blood and the detected gamma delta T were almost entirely of the V delta 2 gamma 9 subset.