Purine catabolism in polymorphonuclear neutrophils. Phorbol myristate acetate-induced accumulation of adenosine owing to inactivation of extracellularly released adenosine deaminase.

Since physiological concentrations (0.1-1 microM) of adenosine influence the functions of human polymorphonuclear neutrophils (PMNs), we investigated the metabolism of adenosine in suspensions of stimulated and unstimulated PMNs. Stimulation with phorbol myristate acetate (PMA, 1 microM), but not by zymosan (0.5 mg/ml) or N-formyl-methionyl-leucyl-phenylalanine (fMLP, 1 microM), provoked an accumulation of endogenous adenosine at a rate of 2.3 +/- 1.0 amol/cell per minute. A similar accumulation was observed with both unstimulated and stimulated PMNs after the addition of deoxycoformycin (dCF, 1-100 microM), an inhibitor of adenosine deaminase. Exogenous adenosine (10 microM) was deaminated at a rate of 9.8 +/- 3.7 amol/cell per minute in control or zymosan or fMLP-stimulated PMN suspensions. This deamination was nearly completely suppressed when the PMNs had been stimulated with PMA. In contrast, the activity of adenosine deaminase in PMN lysates (231 +/- 72 amol/cell per minute) was not modified by PMA stimulation. alpha, beta-Methyleneadenosine 5'-diphosphate (AMPCP, 2.5 mM), an inhibitor of membranous ecto-5'-nucleotidase, profoundly inhibited endogenous adenosine accumulation under all conditions. PMA stimulation also provoked an inactivation of extracellular adenosine deaminase, purine nucleoside phosphorylase, and lactate dehydrogenase in PMN suspensions. We concluded that PMNs, even when not stimulated, continuously produce adenosine by dephosphorylation of extracellularly released adenylates; and that stimulation of PMNs by PMA causes adenosine accumulation owing to the inactivation of adenosine deaminase released by broken cells

Stimulation by glycerate 2,3-bisphosphate: a common property of cytosolic IMP-GMP 5'-nucleotidase in rat and human tissues.

Glycerate 2,3-bisphosphate, a potent stimulator of the cytosolic 5'-nucleotidase which preferentially hydrolyzes IMP and GMP in human erythrocytes (Bontemps et al., 1988, Biochem. J. 250, 687-696), also stimulates the dephosphorylation of IMP in cytosol fractions of rat heart, liver, brain, kidney, spleen and erythrocytes, and of human polymorphonuclear leucocytes, mixed peripheral blood lymphocytes, platelets and fibroblasts. Depending on the cell type, stimulation by 5 mM glycerate 2,3-bisphosphate varied from 1.5- to 12-fold. Where investigated, glycerate 2,3-bisphosphate had an approx. 5-fold higher affinity for the enzyme than its other stimulator, ATP. These observations provide a useful tool to distinguish IMP-GMP 5'-nucleotidase from other 5'-nucleotidases, and suggest a common origin of the cytosolic IMP-GMP 5'-nucleotidase in various tissues

A prospective randomized study of three types of platelet concentrates in patients with haematological malignancy: Corrected platelet count increments and frequency of nonhaemolytic febrile transfusion reactions

We prospectively randomized 51 patients with haematological malignancy requiring platelet concentrates (PCs) to receive either single donor platelet-pheresis products (SD-PC), PCs made from pooled buffy coats (BC-PC) or pooled units of platelets made by the platelet-rich plasma method (PRP-PC). The leucocyte content of each type of PC was 0.33 (0.03-13.5), 5.68 (0.19-99.0) and 365 (65-910) x 106; median (range), respectively; P < 0.0001. All red cell transfusions were leucodepleted by filtration. Statistical comparison of the probability of the occurrence of a nonhaemolytic febrile transfusion reaction (NHFTR) following transfusion of PCs in patients in each group showed a significant decrease for the SD-PC and BC-PC groups (0.031 and 0.038, respectively) when compared with PRP-PC (0.171); P = 0.0001. The actual corrected platelet count increments (CCI) at 1-6 and 18-24 h post-transfusion for all three types of PC did not differ significantly. We conclude that transfusion of PRP-PC is associated with a significant increase in NHFTR