title: Ultrastructural localization of acid phosphatase in rosetted T and B lymphocytes of normal human blood.
abstract: Using electron microscopy and cytochemical techniques, the authors determined the distribution of acid phosphatase (AcPase) within the organelles of lymphocytes from blood rosetted with either neuraminidase-treated sheep erythrocytes (En) or sheep erythrocytes coated with antibody and complement (EACs). Subsequently, the various reactive organelles of the rosetted lymphocytes were counted, affording a comparison of T and B cells. It was found that AcPase was present in approximately 80% of T cells and 45% of B cells and was most frequently observed in secondary lysosomes of varying size and content. Although more T cells than B cells were reactive for AcPase, the extent of reaction in some B cells clearly precludes the use of AcPase for differentiating the two cell lines. It should be recognized that while the En rosetting procedure detects T cells in  a nonselective manner, the EAC rosette is a marker of a major subpopulation of B lymphocytes, ie, those bearing complement receptors. We believe that the distribution of lysosomal enzymes in B and T lymphocytes probably reflects the functional state of individual cells rather than being a reliable indicator of cell lineage. A surprising finding (which could be established only by a fine-structural study) was the fact that 20% of circulating "resting" T cells contained reaction product for AcPase within endoplasmic reticulum and the perinuclear cisterna indicating that these cells are actively synthesizing AcPase, probably due to a foregoing inductive event. Such stimulus could be the result of recent endocytosis of surface receptors in combination with antigen, antibody, or immune complexes and/or recent mitosis, or possibly some unrelated autophagic incident.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism*; D000328:Adult; D001402:B-Lymphocytes / Q000201:enzymology*; D002803:Chondro-4-Sulfatase / Q000378:metabolism; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000276:immunology; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D008854:Microscopy, Electron; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000201:enzymology*
chemical_list: D000135:Acid Phosphatase; D002803:Chondro-4-Sulfatase