The non-specific binding of thermally denatured DNA by healthy human sera in Farr assay with or without addition of dextran sulfate and calcium chloride.

A non-specific DNA binding by human sera was measured in 60 male and female healthy subjects in different ages. Farr assay using thermally denatured mouse embryo [3H]DNA proved a high DNA binding level of 47.9 +/- 5.8% (mean +/- S.D.) on an average of these sera. The addition of dextran sulfate and CaCl2 significantly decreased the mean binding value to 14.7 +/- 4.8% and 6.5 +/- 3.2%, respectively. No significant difference was observed between men and women, or between any age groups from twenties to sixties. The measurement of complement activity in the serum gave no evidence for the participation of complement in the non-specific DNA binding.