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Research Article Free access | 10.1172/JCI106444

Release of vitamin B12—binding protein by human leukocytes in vitro

José Corcino, Stephen Krauss, Samuel Waxman, and Victor Herbert

Department of Medicine, Mount Sinai School of Medicine of the City University of New York, New York 10029

Veterans Administration Hospital, Bronx, New York 10468

Department of Pathology, College of Physicians & Surgeons, Columbia University, New York, New York 10032

Find articles by Corcino, J. in: JCI | PubMed | Google Scholar

Department of Medicine, Mount Sinai School of Medicine of the City University of New York, New York 10029

Veterans Administration Hospital, Bronx, New York 10468

Department of Pathology, College of Physicians & Surgeons, Columbia University, New York, New York 10032

Find articles by Krauss, S. in: JCI | PubMed | Google Scholar

Department of Medicine, Mount Sinai School of Medicine of the City University of New York, New York 10029

Veterans Administration Hospital, Bronx, New York 10468

Department of Pathology, College of Physicians & Surgeons, Columbia University, New York, New York 10032

Find articles by Waxman, S. in: JCI | PubMed | Google Scholar

Department of Medicine, Mount Sinai School of Medicine of the City University of New York, New York 10029

Veterans Administration Hospital, Bronx, New York 10468

Department of Pathology, College of Physicians & Surgeons, Columbia University, New York, New York 10032

Find articles by Herbert, V. in: JCI | PubMed | Google Scholar

Published December 1, 1970 - More info

Published in Volume 49, Issue 12 on December 1, 1970
J Clin Invest. 1970;49(12):2250–2255. https://doi.org/10.1172/JCI106444.
© 1970 The American Society for Clinical Investigation
Published December 1, 1970 - Version history
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Abstract

Human granulocytes (G) contain a vitamin B12-binding protein (B12BP). There is evidence that chronic myelogenous leukemia leukocytes (CMLL) may synthesize B12BP. Our prior studies suggested that intact, living intravascular G synthesize and release such protein into extracellular compartments in vivo.

In the present study, CMLL were incubated in Trisbuffered Hank's basal salt solution (pH 7.2) containing 0.1% human serum albumin to study release of B12BP into the medium. B12BP was released continuously and in increasing amounts over a 5 hr period at 37°C; this release was inhibited almost completely when the cells were incubated at 4°C and by about half as much in the presence of N-ethylmaleimide (1 mmole/liter). Cycloheximide (50 μg/ml) had no effect on the release of B12BP but significantly inhibited incorporation of leucine-3H into leukocyte protein. G incubated with 20 mg/ml of compound 48/80, an experimental histamine-releasing agent, had a 6-fold increase in release of B12BP over a 2 hr period.

Subcellular fractionation studies of human granulocytes demonstrate that most of the B12BP is associated with the granular (20,000 g) layer with an excellent correlation observed between its subcellular distribution and that of acid phosphatase.

These findings suggest that the release of B12BP from G is mediated by an active process and provide further evidence that granulocytes are secretory as well as phagocytic cells.

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