Irradiated Cell Populations Research Articles

Radioresistance of cooperative function of carrier-specific lymphocytes in antihapten antibody responses.

Transfer of lymphoid cells from strain-2 guinea pigs immunized to bovine gamma globulin into syngeneic recipients immunized with dinitrophenyl ovalbumin markedly enhances the secondary antidinitrophenyl response of the recipient to challenge with dinitrophenyl-bovine gamma globulin. This function of the carrier bovine gamma globulin-specific cells is resistant to irradiation with up to 5000 rads, although the capacity of the irradiated cell population to transfer immunologic memory for bovine gamma globulins or to be stimulated by antigen to synthesize DNA in vitro is abolished by this treatment.

Lipid Turnover in an Isolated Population of Irradiated Bone Marrow Cells

In vitro experiments are reported in this paper for the incorporation of ${\rm K}\text{-palmitate-}1\text{-}{\rm C}^{14}$ into triglycerides, diglycerides, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, lysolecithin, and sphingomyelin. At intervals of 1 day or more after total-body irradiation, there was a significant inhibition of the esterification of fatty acids into phospholipids, primarily lecithin. Labeled diglycerides did not increase under these conditions. The labeling of triglycerides in the irradiated marrow continued at essentially the same rate as in the control for the first 2 days after 800 R, after which it, too, was inhibited by ionizing irradiation. We conclude that enzymatic pathways for triglyceride biosynthesis are more resistant to damage by irradiation than are the pathways for the biosynthesis of phosphatides.

CELLULAR GROWTH AND TISSUE RADIOSENSITIVITY: CELL STUDIES IN VITRO AND GENERAL CONCEPTS.

L cells irradiated with various doses of /sup 137/Cs gamma rays were used to study relative cell radiosensitivity at various phases of the population growth cycle. When irradiated population cell counts were expressed as fraction of their respective controls, cell populations of stationary phase origin appeared to be larger than populations of logarithmic phase origin by a factor averaging 30%. Three growth levels (6, 12, and 18 cells) of logarithmic and stationary cells were irradiated, and the dose required to reduce the irradiated cell populations to 0.37 of their respective controls (/sup 37/D) was calculated from the straight line portion of the curves. It was found that as relative cell number increased, the values of the /sup 37/D as well as the difference of these values between logarithmic and stationary origin cells decreased rapidly. Results are interpreted in terms of radiosensitivity. (H.M.G.)