Changes of gamma/delta T cells in blood after radiation therapy for prostatic cancer

The changes of the size of gamma/delta T (gamma delta T) and alpha/beta T (alpha beta T) cell subsets in the blood were examined after radiation therapy (66 Gy) for prostatic carcinoma in 17 men. Following radiation both subpopulations of T cells were reduced to 52% and 36% of starting values, respectively. gamma delta T cells were not replaced four months after radiation therapy, in contrast to alpha beta T cells, which were increased to 47% of initial values. The T alpha beta/T gamma delta ratio was significantly reduced immediately after radiation therapy but was normalised after four months. Blood gamma delta T cells may be reduced for a long time after radiation therapy and this may be true also for gamma delta T cells in irradiated epithelial organs and tumours.