Immunolocalization of human cystatins in neutrophils and lymphocytes

The endogenous inhibitors of cysteine proteinases, cystatin A and cystatin B, have been localized in sections of human liver by indirect immunofluorescence microscopy. Cystatin A was localized in neutrophils and cystatin B was found in lymphocytes. Both types of cell were present in the blood vessels and within the sinusoids between the parenchymal cells. Cystatin A was also found in some of the parenchymal cells surrounding the blood vessels but, in contrast to the uniform fluorescence of the leucocytes, the staining in the parenchymal cells was granular and rather irregular.