Concentration of C1 inhibitor in sera of healthy blood donors as studied by immunoenzymatic assay.

One hundred and forty sera from healthy blood donors (age 19-30 years) were studied for the concentration of C1 inhibitor. The determinations were performed by enzyme-linked immunosorbent assay with the use of specific anti-C1 inhibitor antibodies fixed to the wells of a microplate and peroxidase labeled as the second layer. The geometric mean of the C1 inhibitor value was 0.25 g/l with a standard deviation of 0.09 and a standard error of 0.0077 g/l while the median and mode values were equal to 0.27 g/l. The technique is relatively simple and can be used for the screening of hereditary or acquired angioedema. The technique can be applied also for the study of population differences in the C1 inhibitor concentration and for the study of its synthesis in in vitro systems.