Stimulatory effect of low dose X-irradiation on the expression of the human T lymphocyte CD2 surface antigen

We investigated the early effects of low doses of ionizing radiation on the CD2 gene expression in normal human T lymphocytes in order to clarify if low-dose ionizing radiation has an enhancing and/or stimulatory effect on the immune response. The results indicate that even low doses 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 of CD2 mRNA is observed in X-irradiated cells compared with non-irradiated, a fact that is attributed mainly to transcriptional activation of the CD2 gene and not to stabilization of preformed mRNA.