Fractionation of the non-histone proteins of antigen-reactive human lymphocytes: Criteria for the specificity of antigen uptake

Non-histone proteins were separated from the nuclei of lymphocytes for the purpose of testing if antigen, following antigen uptake, could be localized within this fraction. Human lymphocytes were disrupted by N₂ cavitation, the nuclei isolated by differential centrifugation, the chromatin purified, and the DNA separated from chromatin proteins by chromatography on Bio-Gel A 5M in the presence of 4 M guanidine-HCl. Non-histone proteins were separated from the histones by chromatography on CM-Sephadex C-50 by a stepwise elution. Non-histone and histone proteins were obtained in satisfactory purity as shown by amino acid analysis and gel electrophoresis. Labeled antigen could be separated unaltered following its incubation with T-lymphocytes. On the other hand, antigen mostly degraded but still capable of precipitating with antibody was separated bound to the non-histone proteins of B-cells. Antigen was not bound to histones.