Studies on the mechanism of chloramphenicol impairment of human leukocyte function

Effect of antibiotics on the phagocytotic and respiratory burst activity of bovine granulocytes

The influence of antibiotics on respiratory burst (phorbol-12-myristate-13-acetate (PMA)-stimulated luminol-enhanced chemiluminescence) and phagocytosis (flow cytometry) by bovine granulocytes was studied in vitro. Phagocytosis was impaired by 1000 micrograms/ml of oxytetracycline, chloramphenicol, erythromycin and spiramycin. All antibiotics, except sulphadiazine, decreased chemiluminescence at 1000 micrograms/ml or lower concentrations. Enrofloxacin increased chemiluminescence. The inhibition by oxytetracycline and danofloxacin was due to absorption of the light emitted by luminol at 425 nm. Oxytetracycline, ceftiofur, spiramycin and erythromycin affected the myeloperoxidase-H2O2-halide system. Ceftiofur, penicillin and danofloxacin showed scavenging effects on H2O2 and OCI. Penicillin and ceftiofur might interfere with luminol. Chloramphenicol, penicillin and ceftiofur affected the production of superoxide radicals. In summary, the observed effects of antibiotics might be of importance during treatment of infectious diseases in normal and immunocompromised animals. However, before classifying a drug as immunosuppressive, attention has to be paid to possible interference with the chemiluminescence assay.

Mammary leukocyte response to drug therapy

The possibility exists that antibiotics and anti-inflammatory agents will be used indiscriminately in attempts to reduce leukocyte or somatic cell counts in mammary secretions to conform with Interstate Milk Shippers quality standards for raw milk to be implemented July 1, 1986. Recent in vivo studies evaluating the effect of intramammary drug injection on milk leukocytes confirmed previous in vitro investigations demonstrating that certain drugs have a significant effect on leukocyte antimicrobial activity. Antibiotics commonly included in commercial infusion products used in this country such as penicillin G, semisynthetic penicillins, the mycins, cephalosporins, and sulfonamides did not affect leukocyte function. However, some drugs were detrimental, notably chloramphenicol, tiamulin, tetracycline, gentamicin, rifampicin, amikacin, and nitrofurantoin. In vitro investigations on the use of anti-inflammatory agents demonstrated that methylprednisolone had a stabilizing effect on leukocytes by maintaining viability and reducing degranulation, whereas flumethasone was detrimental to cell viability. The nonsteroid agent, ibuprofen, decreased viability and increased degranulation but also increased phagocytosis and bacterial killing. Intramammary infusion of anti-inflammatory agents was generally ineffective in lowering somatic cell counts of endotoxin-infused quarters, but certain drugs may be advantageous in limiting milk production losses during udder inflammation.

Effect of amoxycillin and doxycycline on function of human granulocytes tested in vitro and on chemotaxis of granulocytes from rabbits given the two antibiotics

The effect of amoxycillin and doxycycline on human granulocyte function was studied in vitro. The antimicrobial agents were added to tests of chemotaxis, random motility, yeast phagocytosis, and killing, at progressing concentrations. The effect was also evaluated in vivo by measuring chemotaxis and random motility (agarose technique) of granulocytes from rabbits injected with these antibiotics. Amoxycillin was shown to have a slightly stimulating effect on chemotaxis, demonstrable only at the highest concentration tested (100 micrograms/ml), and no effect on the other variables. Doxycycline had a dose-related inhibitory effect on chemotaxis, random motility, and phagocytosis, and no effect on killing. Chemotaxis and random motility were slightly, but not significantly, stimulated in vivo when rabbits were given amoxycillin. Chemotaxis (but not random motility) was significantly impaired when the rabbits were given doxycycline.

Study of phagocytic function with a quantitative nitroblue-Tetrazolium (NBT) reduction test in diabetes mellitus

In 40 patients suffering from diabetes mellitus and in 18 healthy volunteers the phagocytic function was investigated using a quantitative NBT test. The NBT reduction was significantly lower in diabetes than in healthy donors irrespective of affliction with other dermatoses. A significant correlation was found between the severity and hence the insulin dependency of diabetics and the NBT-reductive capacity.

Effect of iron on leukocyte function: inactivation of H2O2 BY IRON

We investigated the effect of FeSO4 on phagocytosis-associated, increased oxidative metabolism via the hexose monophosphate shunt, with special attention to its effect on H2O2 levels. The availability of glutathione eroxidase and glutathione reductase for H2O2 disposal and hexose monophosphate shunt stimulation also are evaluated. The results show an impairment of phagocytosis-associated hexose monophosphate shunt activity together with an increase both of resting and phagocytosing formate oxidation. These apparently paradoxical findings are resolved by demonstrating a direct enhancement of formate oxidation by FeSO4 in a cell-free system. In addition, measurement of H2O2 concentrations via scopoletin fluorescence shows reduction of H2O2 by Feso4. There is no effect on either glutathione peroxidase or glutathione reductase activities. These data suggest that one mechanism of FeSO4 imairment of microbicidal activity is by its removal of H2O2.