Neutralising effect of histone fractions from human leukocyte nuclei on heparin

Histone fractions from human leukocyte nuclei can interact with heparin to form complexes measurable by means of laser nephelometry. Histone fractions have not all the same affinity to bound heparin and the lysinrich histone fraction cannot interact with heparin. The formation of histone/heparin complex depends not on the temperature between 20 degrees--37 degrees C or on the pH between 7--8.2. The precision of the method was estimated. The significance of the histones/heparin interactions for an assay method for control to the biological activity of heparin preparations and a possible biological role of these interactions in vivo was briefly discussed.