Studies of long-term continuous irradiations using daily doses ranging from 0.07 to 0.30 Gy on the B lymphoid system of the rat.

The effects of a continuous exposure to cobalt gamma rays administered to rats at a daily dose of 0, 0.07, 0.12, 0.20 or 0.30 Gy for a period of up to 90 or 135 days, have been observed on their B lymphocyte populations and on their immunoglobulin serum levels. The effects increase with the daily dose and the duration of irradiation. At a daily dose of 0.07 Gy, no clear effect was observed. The depletion was almost negligible after 30 days at a daily dose of 0.12 Gy, but visible after all other doses and durations. However, a clear difference in susceptibility was observed between the marginal zone B compartment and the follicular one, the former being much more affected by the radiation than the second.