A note on the demonstration of nuclear acidic HCl insoluble proteins in peripheral blood smears.

The present study deals with the conditions necessary for the specific demonstration of nuclear acidic HCl insoluble proteins is smeared peripheral leucocytes by means of a simple cytochemical procedures. These proteins can be very easily selectively demonstrated by staining with Azure C or Toluidine blue above pH 6, after the fixation of smears with methanol, extraction of histones, nucleic acids (with HCl, TCA) and treatment with formaldehyde. The double fixation with methanol and formaldehyde facilitated specific extraction of nuclear acidic HCl insoluble proteins of smeared leucocytes with pepsin. The nuclear acidic HCl insoluble proteins are present in leucocytes in interchromatin areas and their isoelectric point determined by cytochemical procedure is pH 6.