Molecular size of the Rh0(D) antigen of the human erythrocyte in situ by radiation inactivation.

Radiation inactivation was used to determine the molecular size of the RhO(D) antigen of isolated membranes and of the intact human erythrocyte. Isolated membranes were frozen and irradiated at -50 degrees C. After thawing, the bound 14C-anti-D was measured and the log residual Rh(D) antigen activity was plotted against the radiation dose. A mol. wt of 60,000 was calculated. Intact human erythrocytes frozen in the presence of cryoprotective reagents were also studied. Rh(D) antigen inactivation occurred as a single exponential function of radiation dose which also yielded a mol. wt of approx. 56,000 upon analysis by classical target theory.