The Effect of X-rays on the Precursors of Antibody Forming Cells (B Cells) as Measured with the in Vitro Limiting Dilution Assay

Summary

The effect of X-irradiation upon murine antibody-forming cell precursors (B cells) was established in cultures of spleen cells stimulated with the B cell mitogen lipopolysaccharide (LPS). At day 5 and 7 the numbers of IgM- and IgG2-secreting cells were determined in cultures of irradiated and nonirradiated spleen cells. From these numbers a D_o of 0·6 – 1·2 Gy for the IgM, and of 0·9 – 2·1 Gy for the IgG2 response was calculated. Similar D_o values were obtained under limiting dilution culture conditions. In the limiting dilution assay the effect of irradiation upon the size of the IgM-producing clones could also be determined. It was found that irradiation reduced the number of LPS-reactive B cells without affecting the size of the clones produced by the surviving cells.