STIMULATORY EFFECT OF LOW-DOSE X-IRRADIATION ON THE EXPRESSION OF THEHUMAN T-LYMPHOCYTE CD2 SURFACE-ANTIGEN

We investigated the early effects of low doses of ionizing radiation o n the CD2 gene expression in normal human T lymphocytes in order to cl arify if low-dose ionizing radiation has an enhancing and/or stimulato ry effect on the immune response. The results indicate that even low d oses of X-irradiation strongly enhance the appearance of CD2 antigen, both in PHA-stimulated and in resting T lymphocytes as demonstrated by a rosette assay or by immunofluorescence. Moreover, an accumulation o f CD2 mRNA is observed in X-irradiated cells compared with non-irradia ted, a fact that is attributed mainly to transcriptional activation of the CD2 gene and not to stabilization of preformed mRNA.