Effects of [alpha]-particle radiation on rat tracheal epithelial cells

By a combination of methods, which included flow cytometry and magnetic cell sorting, we have demonstrated that the cells of the rat tracheal epithelium which have the greatest proliferative capacity in culture and in vivo are the basal cells. Because of these findings it seems reasonable to suppose that the basal cells are the most likely target for the action of α-particle radiation in pseudostratified respiratory epithelium. This hypothesis is further supported by the finding that the basal cells are the cells which appear to respond to the tumor promoter 12-O-tetra-decanoylphorbol- 13-acetate. The effects of ²¹⁰Po α-particles on the survival and oncogenic transformation of rat tracheal epithelial cells in suspension were investigated. Since these effects were assayed in culture, the results pertain to the reaction of only the basal cells to irradiation. The results indicate that a-particles are extremely cytotoxic in that a track segment of 4 μm, on average, is sufficient to cause the reproductive death of basal cells. This finding is supported by similar results obtained with two cell lines, Mv1Lu and CHO-K1 BH₄. Production of proliferating epithelial foci by α-particles was not distinguishable from control and sham treatments. These results are in direct conflict with many of the results that have been obtained with C3H 10T1/2 cells in similar transformation assays. Some possible reasons for these disparities are discussed and supporting evidence is provided.