Effect of tetracycline, polymyxin B, and rifampin on phagocytosis

Low concentrations of oxytetracycline, doxycycline, or minocycline (< 10 ,ug/ml) did not influence in vitro polymorphonuclear leukocyte random migration, chemiluminescence, or glucose oxidation. At high concentrations of doxycycline or minocycline (> 10 ,ug/ml), chemiluminescence and glucose oxidation were impaired. High concentrations of doxycycline also reduced random migration. Oxytetracycline did not influence these functions in concentrations up to 100 pug/ml. The inhibiting effect of doxycycline and minocycline was abolished when 4 mM Mg2+ was added to the reaction mixture, and 4 mM Ca2+ partly restored minocycline-inhibited polymorphonuclear leukocyte functions. This indicates that the major effect of tetracyclines on in vitro polymorphonuclear leukocyte functions is mediated by their divalent cation chelating effect and that the results of in vitro experiments are highly dependent on the concentration of divalent cations in the reaction mixtures. The difference between the tetracyclines may be due to differences in lipid solubility, with solubility being highest for minocycline and lowest for oxytetracycline, or to different divalent cation chelating ability.Polymorphonuclear leukocytes (PMNLs) represent cornerstones of host defense against infections (2). The possibility that antimicrobial agents may impair PMNL functions is of particular interest since these drugs are frequently administered to patients with enhanced susceptibility to infection. Several studies have focused on the effect of tetracyclines on PMNL function, but the results of these studies are not consistent. In some studies, (4,8,12,18,24) doxycycline has been shown to reduce PMNL chemotaxis (4, 12), phagocytosis (8, 19), or bactericidal activity (18,24) or all three of these. However, in another study, Forsgren and Gnarpe have failed to demonstrate any effect on these functions (7). Oxytetracycline has been reported not to inhibit PMNL functions (7). We have previously shown that doxycycline does not reduce in vivo PMNL migration to skin chambers (10) and have indicated that the impairment of PMNL functions measured in vitro may be due to photo-induced production of toxic oxygen species or due to the divalent cation chelating effect of tetracyclines or both. The aim of the present study was to examine the influence of oxytetracycline, doxycycline, and minocycline on human PMNL functions in the presence of high and low divalent cation concentrations.MATERIALS AND METHODSLeukocytes. Leukocytes were obtained by dextran sedimentation of heparinized blood (18 U of heparin per ml of blood) from healthy volunteers. After centrifugation of the supernatant (500 x g, 5 min) the red cells were lysed with ammonium chloride solution (0.15 M). The leukocytes used for chemiluminescence (CL) and glucose oxidation assays were washed twice in phosphate-buffered saline. A differential count was made, and the cells were resuspended in Hanks balanced salt solution, containing 20 mg of bovine serum albumin per ml, to make concentrations of 107 PMNLs per ml....

supporting

confidence: 50%

Influence of tetracyclines on human polymorphonuclear leukocyte function

Glette¹,

Sandberg²,

Hopen³

et al. 1984

“…Conversely, a lack of inhibition by tetracycline on PMNL phagocytosis has also been documented (7). These discrepancies may be due to the widely different methods used to quantitate phagocytosis.…”

Section: Methodsmentioning

confidence: 99%

Effect of antimicrobial agents on human polymorphonuclear leukocyte microbicidal function

Welch¹,

Davis²,

Thrupp³

1981

The effect of 19 antimicrobial agents on human polymorphonuclear leukocyte function was evaluated by chemiluminescence assays, yeast phagocytosis and killing, and lactate dehydrogenase release. Tetracycline and trimethoprim inhibited chemiluminescence and reduced killing at therapeutic concentrations of 2 microgram/ml. Cephalothin inhibited yeast killing at a concentration of 20 microgram/ml, but a significant depression of polymorphonuclear leukocyte chemiluminescence was encountered only at higher levels of 200 microgram/ml. The inhibition shown by these drugs was reversible. None of the other antimicrobial agents tested demonstrated inhibition of chemiluminescence, phagocytosis, or killing at usual clinical serum levels. No antimicrobial agent tested caused release of lactate dehydrogenase from polymorphonuclear leukocytes. The results suggest that therapeutic concentrations of tetracycline, trimethoprim, and cephalothin may inhibit optimal polymorphonuclear leukocyte microbicidal function.

“…It is also evident that light conditions may influence the results of in vitro PMNL function tests carried out in the presence of tetracyclines. Accordingly, our observations may explain some of the differing results of previous studies in this field (15,18,19).…”

Section: Discussionmentioning

confidence: 51%

“…However, studies with tetracyclines are inconsistent. High concentrations of chlortetracycline, doxycycline, and minocycline have been reported to markedly inhibit in vitro PMNL functions, whereas similar effects have not been demonstrated for oxytetracycline or tetracycline hydrochloride (15,18,19). We have previously shown that low concentrations (<10 pug/ml) of tetracyclines had no influence on in vitro PMNL functions, whereas high concentrations inhibited these functions.…”

mentioning

confidence: 77%

Effect of tetracyclines and UV light on oxygen consumption by human leukocytes

Glette¹,

Sandberg²,

Haneberg³

et al. 1984

When polymorphonuclear leukocytes were stimulated with zymosan, a sharp rise in oxygen consumption was observed. In the presence of doxycycline, we observed a further increase in oxygen consumption when the phagocytosing cells were exposed to UV light. When the light was turned off, oxygen consumption of the cells almost ceased, indicating photodamage to polymorphonuclear leukocytes during irradiation. Irradiation of the polymorphonuclear leukocytes for 20 min in the presence of doxycycline (10 ,Ig/ml) before phagocytosis completely abolished the rise in oxygen consumption initiated by zymosan. Demethylchlortetracycline and light exposure also caused a marked reduction of polymorphonuclear leukocyte oxygen consumption, whereas oxytetracycline, lymecycline, chlortetracycline, and minocycline had only a slight or no photosensitizing effect. The photodamage induced by doxycycline and demethylchlortetracycline was inhibited by azide and enhanced in deuterium oxide. This was in accordance with singlet oxygen-mediated damage.Polymorphonuclear leukocytes (PMNLs) are cornerstones of host defenses against infections. During phagocytosis and intracellular killing of bacteria by PMNLs, oxygen consumption takes place (16,20), and toxic oxygen radicals essential for the killing of phagocytosed bacteria (22, 27) are generated (1, 5). Several drugs, including tetracyclines, have been shown to influence these functions. However, studies with tetracyclines are inconsistent. High concentrations of chlortetracycline, doxycycline, and minocycline have been reported to markedly inhibit in vitro PMNL functions, whereas similar effects have not been demonstrated for oxytetracycline or tetracycline hydrochloride (15,18,19). We have previously shown that low concentrations (<10 pug/ml) of tetracyclines had no influence on in vitro PMNL functions, whereas high concentrations inhibited these functions. This inhibition was abolished when increasing concentrations of divalent cations were added to the medium (8, 9).Besides the chelating effect, tetracyclines may also influence PMNL function by other mechanisms. It is well known that these drugs can cause skin lesions in patients exposed to the sun (4,7,13,14,21,28), and we have recently shown that doxycycline can induce photodamage to PMNLs (24). In the present study, we examined the effect of six tetracyclines on PMNL oxygen consumption in the presence of UV light. In addition, the mechanism of tetracycline-induced photodamage was studied.MATERIALS AND METHODS Preparation of cells. Ten parts heparinized (18 U/ml) blood mixed with three parts dextran solution (60 mg/ml; Pharmacia, Uppsala, Sweden) were sedimented at room temperature. After centrifugation of the supernatant (500 x g, 5 min) the erythrocytes were lysed with ammonium chloride (0.15 M; pH 7.4), and the leukocytes (of which 60 to 80% were PMNLs) were washed twice in phosphate-buffered saline. The leukocytes were suspended in phosphate-buffered saline (pH 7.3) to a concentration of 107 cells per ml. Tetracycline was added to the ...