Adenosine deaminase, which is essential for lymphoid differentianon and function, has previously been considered to be a cytosolic enzyme. In this report we demonstrate that it can be found associated with the plasma membrane of lymphocytes. By means ofi,mmunological techniques using both light and electron microscopy, adenosine deaminase was localized on the external side of the plasma membrane of normal lymphocytes and monocytes. Since the enzyme
To standardize the results obtained in PML/RAR␣ RT-PCR detection by laboratories of hospitals involved in the SpanishProgram for Treatment of Hematological Malignancies (PETHEMA) LPA-96, designed for the treatment of acute promyelocytic leukemia (APL), cDNA samples obtained by reverse transcription of RNA from bone marrow samples of patients with APL were sent to participating laboratories. During the first year of this external quality assessment trial nine samples were tested by a maximum of 12 laboratories. The control gene was satisfactorily amplified in 90% of the samples (62 of 69 samples), supporting the adequacy of the cDNA to be used as control sample. There was an 83% concordance between laboratories for PML/RAR␣ detection with similar results for the type of PML/RR␣ rearrangements. However, 17% disagreement still remained, attributable to low sensitivity or inadequacy of methods followed. The results stressed the need for implementation of an external quality assessment scheme to ensure the standardization of the results.
Menosine deaminase has been localized in the plasma membrane of erythrocytes and platelets by means of immunelogical techniques using light and electron miaescopy with cells in suspension. In erythrocytes, adenosine deaminase is associated with the external side of the plasma membrane. In platelets, the enzyme is associated with the external side of the plasma membrane, which is known to extend through
The levels of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), lactic dehydrogenase (LDH), and LDH isoenzyme patterns (LD1 to LD5) have been measured in lymphocyte extract from 28 patients with B-chronic lymphocytic leukemia (B-CLL). The activities of ADA, PNP, and LDH have been correlated with two morphological groups of B-CLL classified according to the percentage of large, nongranular, atypical lymphocytes (AL) in peripheral blood: "typical" B-CLL (less than 10% of AL, 21 cases) and "atypical" B-CLL (10-25% of AL, seven cases). Patients with atypical B-CLL had significantly (P less than 0.001) higher activities of ADA (0.46 +/- 0.17 U/10(9) cells), PNP (1.74 +/- 1.0 U/10(9) cells), and LDH (48.3 +/- 9.7 U/10(9) cells) than patients with typical B-CLL (ADA, 0.29 +/- 0.1 U/10(9) cells; PNP, 0.58 +/- 0.23 U/10(9) cells; and LDH, 29 +/- 10 U/10(9) cells). In addition, the "treatment-free period" was also significantly (P less than 0.025) shorter in the group of atypical B-CLL compared with the typical B-CLL group. No clear-cut statistical differences in lymphocyte surface markers or in several other prognostic factors between the two subgroups of B-CLL were found. The present study supports the idea that in B-CLL the simultaneous determination of ADA, PNP, and LDH might be helpful in better understanding the pathophysiology, prognosis, and natural history of the disease.
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