Effect of gamma-irradiation on the effector function of T lymphocytes in microbial control.

A chlamydial-specific T cell clone, capable of inhibiting the growth of infectious Chlamydia in vivo and in vitro, was employed to investigate the effect of gamma-irradiation on the ability of effector T cells to control infections. Clone 2.14-0 (CD4+), specific for the Chlamydia trachomatis biovar agent of mouse pneumonitis (MoPn), was irradiated with varying doses (0, 2.5, 5.0, 10.0, 20.0 and 40.0 Gy) and its biological functions and ability to inhibit the intraepithelial growth of MoPn were assessed. The results revealed that although gamma-irradiation drastically reduced the proliferative response of the clone to antigen, it did not affect the phenotype and the effector function of inhibiting chlamydial growth. The preservation of anti-chlamydial function after gamma-irradiation correlated with the retention of IFN-gamma and TNF-alpha secretion in response to antigenic stimulation. We conclude that the biologic functions of T cells requiring proliferation and differentiation are more likely to be adversely affected by gamma-irradiation on the short-term, but the effector functions, possibly associated with cytokines and cytolysis, may be preserved among persisting effector T cells in an irradiated individual.