title: Localization of GTP cyclohydrolase I in human peripheral blood smears using a specific monoclonal antibody and an immune-alkaline phosphatase labeling technique.
abstract: GTP cyclohydrolase I, the enzyme catalyzing the first step in the cofactor biosynthesis for the aromatic amino acid hydroxylases, has been localized in situ. By the use of a monoclonal antibody specific to human GTP cyclohydrolase I, the enzyme has been visualized immuno-enzymatically by alkaline phosphatase monoclonal anti-alkaline phosphatase labeling. In routine blood smears lymphocytes, monocytes/macrophages, and granulocytes show strong intraplasmatic staining. Premature erythrocytes show clear staining of the reticulated cytoplasmatic structure, while mature erythrocytes are completely negative. Neither is there any staining for GTP cyclohydrolase I in the blast cells of a case of T-cell acute lymphoblastic leukemia. These results closely confirm the prior finding that mature erythrocytes as well as most malignant mononuclear cells lack GTP cyclohydrolase I activity, and they indicate that in these cells the enzyme protein may be absent.
authors.affiliation: Department of Pediatrics, University of Zurich, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Schoedon
authors.forename: H C
authors.initials: HC
authors.lastname: Curtis
authors.forename: A
authors.initials: A
authors.lastname: Niederwieser
mesh_terms: D000469:Alkaline Phosphatase; D000619:Aminohydrolases / Q000097:blood*; D000911:Antibodies, Monoclonal; D001708:Biopterins / Q000031:analogs & derivatives* / Q000096:biosynthesis; D001773:Blood Cells / Q000201:enzymology*; D006136:GTP Cyclohydrolase / Q000097:blood*; D006801:Humans; D007124:Immunoenzyme Techniques
chemical_list: D000911:Antibodies, Monoclonal; D001708:Biopterins; D000469:Alkaline Phosphatase; D000619:Aminohydrolases; D006136:GTP Cyclohydrolase; C003402:sapropterin