Scand. J. Immunol. 35, 121, 1992
Letter to the Editors Dear Sirs, I read with great interest the article by Ketzinel et al. entitled 'Regulation of Human Interleukin-2 and Interferon-Gamma Gene Expression by Suppressor T Lymphocytes' which appeared in the Scandinavian Journal of Immunology, 33, 593-605, 1991. The authors have studied the effects of gamma irradiation on IL-2 production and IL-2 mRNA expression by human tonsillar lymphocytes. They reported that gamma irradiation enhanced IL-2 gene expression by preventing the activation of suppressor T cells. They also indicated that the observed increase in IL-2 concentration was due to increased production by radioresistant T-helper cells. In addition, they postulate that the increase was not caused by the removal ofIL-2 utilizing suppressor T cells; however, they did not provide any data to support the latter claim. Our paper entitled 'Radiation Causes Increased Production and Decreased Utilization of IL-2 in Human Mononuclear Cells', which was published in Cytokine, 2, 35-44, 1990, has almost identical observations on radiation kinetics, IL-2 mRNA expression and IL-2 production by irradiated, PHAstimulated human peripheral blood mononuclear cells. We attributed the same mechanism that Ketzinel et al. mentioned in the above paper: inactivation of radiosensitive suppressor T cells during the process of irradiation was responsible for the observed increase in IL-2 mRNA expression and IL-2 secretion in radioresistant helper T cells. This was due to the release of helper T eells from suppression by putative suppressor factor(s) normally produced by the radiosensitive suppressor T cells. In contrast to the above authors' postulation that the increase was not caused by the removal of IL-2 utilizing cells, we have reported that it was also due to decreased utilization of secreted IL-2 by the irradiated cells. This was demonstrated by proliferative and kinetic studies and also by reciprocal mixing experiments utilizing culture supernatants and cells, that were obtained before and after irradiation and PHA stimulation. We hope that this information will help your readers in further understanding this field. M. Venkataraman, BVSc, MSc, PhD, Department of Medicine, Mount Sinai Hospital Medical Center, Chicago, IL 60608, USA
Letter to the Editors Dear Sirs, I read with great interest the article by Ketzinel et al. entitled 'Regulation of Human Interleukin-2 and Interferon-Gamma Gene Expression by Suppressor T Lymphocytes' which appeared in the Scandinavian Journal of Immunology, 33, 593-605, 1991. The authors have studied the effects of gamma irradiation on IL-2 production and IL-2 mRNA expression by human tonsillar lymphocytes. They reported that gamma irradiation enhanced IL-2 gene expression by preventing the activation of suppressor T cells. They also indicated that the observed increase in IL-2 concentration was due to increased production by radioresistant T-helper cells. In addition, they postulate that the increase was not caused by the removal ofIL-2 utilizing suppressor T cells; however, they did not provide any data to support the latter claim. Our paper entitled 'Radiation Causes Increased Production and Decreased Utilization of IL-2 in Human Mononuclear Cells', which was published in Cytokine, 2, 35-44, 1990, has almost identical observations on radiation kinetics, IL-2 mRNA expression and IL-2 production by irradiated, PHAstimulated human peripheral blood mononuclear cells. We attributed the same mechanism that Ketzinel et al. mentioned in the above paper: inactivation of radiosensitive suppressor T cells during the process of irradiation was responsible for the observed increase in IL-2 mRNA expression and IL-2 secretion in radioresistant helper T cells. This was due to the release of helper T eells from suppression by putative suppressor factor(s) normally produced by the radiosensitive suppressor T cells. In contrast to the above authors' postulation that the increase was not caused by the removal of IL-2 utilizing cells, we have reported that it was also due to decreased utilization of secreted IL-2 by the irradiated cells. This was demonstrated by proliferative and kinetic studies and also by reciprocal mixing experiments utilizing culture supernatants and cells, that were obtained before and after irradiation and PHA stimulation. We hope that this information will help your readers in further understanding this field. M. Venkataraman, BVSc, MSc, PhD, Department of Medicine, Mount Sinai Hospital Medical Center, Chicago, IL 60608, USA
