Gold complexes and activation of human polymorphonuclear leukocytes. Dissociation of changes in membrane potential and oxidative burst.

The effects of the gold compounds on the alteration of membrane potential of polymorphonuclear leukocytes (PMN) in response to various stimulants have been compared with their effects on the oxidative burst. The present studies have shown that gold complexes [auranofin (AF), aurothiomalate (Autm), aurocyanide (Au(CN)2-)] have contrasting effects on the membrane potential of 3,3'-dipentyloxacarbocyanine [di-O-C5(3)] loaded PMN. Au(CN)2- at concentrations which inhibit the oxidative burst of PMN did not affect the membrane depolarization after activation of PMN by phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl phenylalanine (FMLP); Autm slightly stimulated the oxidative burst but had no effect on the depolarization of PMN. In contrast, AF inhibited the depolarization of stimulated PMN to an extent depending upon the concentration of AF, the time of preincubation and the stimulus. The membrane depolarization of PMN caused by PMA, FMLP and concanavalin A (ConA) was inhibited by AF (5 microM) but the depolarization induced by calcium ionophore (A23187) was not affected. AF at the same conditions inhibits the oxidative burst of PMN induced by all these single stimuli including the calcium ionophore. Dissociation of membrane depolarization and superoxide generation caused by AF was also seen in PMN activated by two stimuli. AF (5 microM) had little initial inhibitory effect on the oxidative burst of PMN stimulated by combinations of PMA and ConA or PMA and FMLP whereas it almost totally blocked the depolarization caused by these combinations. Preincubation of cells with 5 microM AF for less than 5 min prior to the addition of PMA allowed membrane depolarization which was followed rapidly by repolarization. None of the gold complexes studied had any effect on the resting membrane potential of PMN.

Auranofin inhibits the activation pathways of polymorphonuclear leukocytes at multiple sites.

In order to characterize the mechanism by which the anti-rheumatic gold complex auranofin (AF) affects the functions of resting and activated polymorphonuclear leukocytes (PMN) the following studies were performed: (1) The effect of AF on the major processes involved in the respiratory burst of PMN: glucose transport and phosphorylation; hexose monophosphate (HMP) shunt activity in intact cells and in a cell-free system; superoxide production by particulate fractions and intact PMN measured as lucigenin-dependent chemiluminescence. (2) A comparison of the effects of AF added to the PMN before, at the time of, or subsequent to the stimulants [N-formyl-methionyl-leucyl phenylalanine (FMLP), concanavalin A (ConA), calcium ionophore (A23187) and phorbol myristate acetate (PMA)]. (3) The effect of AF on PMN activated by two stimulates (PMA, ConA) added sequentially. AF (0.1-10 microM) caused a dose-dependent inhibition of lucigenin-dependent chemiluminescence regardless of the activator (FMLP, ConA, A23187, PMA) when AF was added before the activator. In contrast, when AF was added to PMN after stimulation, it inhibited only the chemiluminescence of PMN stimulated by PMA. Furthermore, the chemiluminescence was largely unaffected by AF in sequentially activated PMN. The relative sensitivity to AF of the various processes studied indicates that blockade of the activation signal appears to be responsible for inhibition of the respiratory burst of PMN.

The effect of aurothiomalate on the oxidative burst of polymorphonuclear leukocytes varies with the quantity of drug in myocrisin ampoules.

The antirheumatic drug, sodium aurothiomalate (GSTM), is not a well defined substance and chemical changes occur in the heat sterilization of the commercial ampoules (Myocrisin). In a comparison of the pharmacological properties of Myocrisin with freshly prepared solutions of GSTM, their effects on the chemiluminescence of polymorphonuclear leukocytes (PMN) activated by phorbol myristate acetate (PMA) were studied. Chemiluminescence was measured in the presence of GSTM from solid material and from Myocrisin ampoules. Myocrisin from 1 and 5 mg ampoules and GSTM in fresh solutions heated at 95 degrees C for 30 min inhibited chemiluminescence, whereas Myocrisin from the higher strength (10-50 mg) ampoules and GSTM in unheated solutions showed no effect at low concentrations and enhancement of chemiluminescence at higher concentrations. Since the gold complexes present in the different strength Myocrisin ampoules do not have identical biological effects, the use of GSTM in investigational studies should involve consideration of its source.

The activation of gold complexes by cyanide produced by polymorphonuclear leukocytes--I. The effects of aurocyanide on the oxidative burst of polymorphonuclear leukocytes.

It has been suggested that the antiarthritic gold complex, aurothiomalate (Autm), is activated by its conversion to aurocyanide by polymorphonuclear leukocytes (PMN) which generate cyanide from thiocyanate. In an examination of this hypothesis, a study has been conducted on the effects of aurocyanide on the oxidative burst of polymorphonuclear leukocytes (PMN) and monocytes activated by phorbol myristate acetate (PMA). Aurocyanide produced delayed inhibition of the oxidative burst as shown by its effect on both lucigenin and luminol-dependent chemiluminescence and on the production of superoxide. It was a more potent inhibitor of luminol-dependent chemiluminescence than free thiomalate and other by-products of the reaction between Autm and cyanide. Aurocyanide had a biphasic effect on the PMA-stimulated hexose monophosphate shunt of PMN, with enhancement at 0.1 microM and inhibition at 10 and 100 microM. The activity of aurocyanide was also compared with that of auranofin, an orally active gold complex, which inhibits a variety of functions of PMN and monocytes. At low concentrations, auranofin produced delayed inhibition of chemiluminescence in a similar fashion to aurocyanide but at high concentrations was an immediate inhibitor of the oxidative burst.

The effect of immediate polyethylene glycol precipitation on free insulin measurements in diabetic patients with insulin antibodies.

Free insulin (FI) measurements obtained by polyethylene glycol (PEG) precipitation within 3 min of drawing the blood sample (FI3) from four insulin-treated diabetic subjects with a wide range of insulin antibodies were compared with published methods of FI estimation. Comparison of FI values obtained by PEG precipitation in assays of replicate samples of the same specimens (N = 9) stored at 4 degrees C for 24 h (EFI) and FI3 were 4.76 +/- 1.5 microU/ml (mean +/- SEM) and 17.13 +/- 4.7 microU/ml, respectively (P less than 0.005). Comparison of FI values obtained in six groups of replicate samples (N = 12, 18 per group, a total of 91 specimens) from these four patients assayed immediately after thawing to 18 degrees C, and incubated at 37 degrees C for 30, 60, and 120 min, and FI3 showed a significant difference in at least one of these four comparisons (mean +/- SEM) in each of these six sample groups. In 18 of 24 comparisons there was a loss of FI when stored samples were used with or without incubation (12 of these were significant at the P less than 0.05-0.001 level), but in 6 of the 24 comparisons there was an increase in the FI against FI3 (3 of these 6 significant at the P less than 0.05-0.01 level). There was a trend toward a greater loss of FI in stored samples with higher FI3 content. Loss of FI during incubation occurred in all groups irrespective of the FI3 content.(ABSTRACT TRUNCATED AT 250 WORDS)

A new application of plasma exchange in insulin dependent diabetes mellitus.

An insulin dependent diabetic patient was resistant to all but central venous insulin administration. For this reason plasma exchange was tried and it restored insulin responsiveness. An anti-insulin IgG antibody was identified in the patient's plasma. Plasma exchange reduced antibody levels and these correlated with daily insulin requirements. Kinetic analysis of anti-insulin antibodies, however caused us to doubt that they were the sole cause of the problem. Although the mechanism remains unclear, plasmapheresis proved to be an effective method of treating this patient's insulin resistance.