Decreased L system amino acid transport and decreased gamma-glutamyl transpeptidase are independent processes in human chronic lymphocytic leukemia B-lymphocytes
✍ Scribed by Timothy J. Woodlock; Richard Brown; Matthew Mani; Lisa Pompeo; Howard Hoffman; George B. Segel; Robert Silber
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 547 KB
- Volume
- 145
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
The L system of amino acid transport is markedly diminished in chronic lymphocytic leukemia (CLL) B-lymphocytes, with a maximal velocity less than 15% that of normal B-lymphocytes. Another membrane-associated function, the activity of the ectoenzyme, gamma-glutamyl transpeptidase (GGT), is diminished in CLL B-cells to 30% that of normal B-cells. In addition to its transpeptidase activity, a role for CGT has been postulated in the transport of amino acids. In the present report, the possible relationship of these two physiologic functions in CLL B-cells was studied. The L system transport defect in CLL is restored by phorbol ester-induced cell maturation; following incubation with 0.1 5 pM tetradecanoyl phorbol acetate (TPA) for 17 hours, the L system initial velocity showed a 20-fold increase. In contrast, there was no significant effect on GGT activity with cell maturation. Furthermore, an antibody which diminished GGT activity by 50% in lymphoid cells did not inhibit L system transport. Thus, the impaired L system amino acid transport and GGT activity appear to be independent processes in CLL B-cel Is.