Observations on the Number of Available C Antigen Sites on Red Cells

Abstract
The number of available C (rh'', Rh 2) antigen sites within the [human] Rh system was estimated using trace-labeled antibody. The results, as available sites per red cell, were as follows: CDe/CDe: 45,700-56,400; Cde/Cde: 42,200; CDe/cDE: 25,500-39,700; CwDe/cde: 21,500-40,000; Cde/cde: 31,100; CDE/cDE: 8500-9800; Cde/cde: 7200. The average equilibrium constant of the anti-C was 0.5 .times. 107 M-1.