Inhibition of granulocyte phagocytosis of Candida albicans by amphotericin B

Effects of naftifine and terbinafine, two allylamine antifungal drugs, on selected functions of human polymorphonuclear leukocytes

Many antimycotic agents negatively affect the natural immune response. Typically, these drugs impair polymorphonuclear leukocyte (PMN) production of superoxide anion, chemotaxis, or the killing of pathogens. Allylamines are a new class of antimycotic compounds with a new mechanism of antifungal action, i.e., inhibition of the fungal squalene epoxidase. The trial that we describe aimed to evaluate the effects of two allylamines, terbinafine and naftifine, on selected functions of PMNs, i.e., superoxide anion production, chemotaxis, and killing of Candida albicans blastospores. Terbinafine and naftifine on their own did not affect superoxide anion production when they were added to PMNs. When PMNs were preincubated with allylamines and were then stimulated by N-formyl-Met-Leu-Phe or phorbol 12-myristate 13-acetate, superoxide anion production was increased (priming effect). Since intracellular free calcium (Ca2+i) is involved in the control of superoxide anion production, we evaluated the effects of the allylamines on the Ca2+i concentration ([Ca2+]i). In the presence of terbinafine or naftifine, the [Ca2+]i increased in a dose-dependent manner; the source of Ca2+i was not extracellular since it was not affected by extracellular calcium chelation with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. In the presence of terbinafine or naftifine, chemotaxis of PMNs was not impaired. Terbinafine and naftifine slightly but significantly increased the killing of C. albicans blastospores (P < 0.05 at 10 and 100 microM). In conclusion, in contrast to imidazole-like drugs, the allylamine antimycotic compounds terbinafine and naftifine enhance selected functions of PMNs.

Effects of antifungal agents on the function of human neutrophils in vitro

Polymorphonuclear leukocytes (PMNs) are an important component of the host defense against fungi. We investigated the influence of five antifungal agents on PMN function and compared them with amphotericin B (AmB). The in vitro effects of AmB, flucytosine, ketoconazole, fluconazole, Sch-39304, and cilofungin (LY121019) on chemotaxis, phagocytosis, oxidative metabolism of PMN as reflected by superoxide anion (O2-) generation, and intracellular killing of Candida albicans blastoconidia were examined. With regard to chemotaxis in response to N-formylmethionyl-leucyl-phenylalanine, as measured by the multiwell chamber method, AmB induced a marked decrease (greater than or equal to 5 micrograms/ml), whereas ketoconazole at 5 micrograms/ml enhance it. Phagocytosis was significantly decreased after pretreatment of PMNs with AmB and Sch-39304 (greater than 5 and 1 to 10 micrograms/ml, respectively). O2- production after stimulation of PMNs with N-formylmethionyl-leucyl-phenyl-alanine was significantly decreased by AmB (greater than 5 micrograms/ml) and enhanced by Sch-39304 (1 to 5 micrograms/ml). In contrast, intracellular killing, as tested by methylene blue staining, was enhanced by ketoconazole (5 micrograms/ml) and Sch-39304 (1 to 5 micrograms/ml). Flucytosine, fluconazole, and cilofungin did not affect PMN function at therapeutic concentrations. The results of this comprehensive study indicate that AmB, flucytosine, cilofungin, and the newer azoles, at safely achievable concentrations, generally do not suppress PMN function at therapeutic enhance selective functions.

Effect of amorolfine (Ro 14-4767/002) on in vitro phagocytosis and intracellular killing of Candida albicans by human neutrophils

The effect of amorolfine (Ro 14-4767/002) on phagocytosis and intracellular killing of Candida albicans blastospores was determined in human neutrophil monolayer assays. At 0.2, 2 and 5 micrograms/ml amorolfine did not have any significant inhibitory or enhancing effect on phagocytosis whether following simultaneous addition of blastospores and drug to the neutrophils, prior treatment of neutrophils for 2 h before addition of blastospores or prior treatment of blastospores for 2 h. Simultaneous addition of amorolfine resulted in a significant increase in killing at all concentrations. This increase was not significantly enhanced by either preincubation of neutrophils or blastospores for 2 h with the drug.

Side effects of antibiotics on immune response parameters and their possible implications in antimicrobial chemotherapy

Antibiotics may influence immune response by quite different ways. By screening the multitude of publications on this subject, the aim of this overview was to arrive at a basic generalizing statement on the relationship between chemical structure or mode of action of antibiotics and the effect on immune response and to get an indication on whether certain in vitro and/or ex vivo parameters could represent comparable effects under clinical conditions. - The influence of antibiotics on immune response may arise by direct effects on immunocompetent cells, i.e. in the absence of microorganisms, or indirectly by changes in structure or metabolic products of germs induced by subminimal inhibitory concentrations (subMIC's). In the former case, stimulatory and inhibitory effects have been observed on phagocytosis and intracellular killing activity, on antibody production including IgE, on different parameters of cellular immunity (e.g. foodpad swelling reaction, MIF-production, mitogen/antigen induced lymphocyte proliferation and delayed type hypersensitivity skin reaction), on mediator production as interleukins or prostaglandins and the expression of corresponding receptors on immunocompetent cells as well as on the course of experimental infections with primary resistant microorganisms. - Indirect effects are related to the influence of subMIC's of antibiotics on the morphology and structure of microorganisms, on their antigenicity/immunogenicity or on their serosensitivity and enzyme and toxin production. - This overview shows that - according to the actual knowledge - antibiotics may exhibit immunological side effects which, however, can not strictly be attributed to certain chemical structures or to a certain mode of action. - It has to be considered that a literary study comparing the results of different authors is rendered difficult by the often nonhomogeneity of experimental procedures and the fact that little is known yet about immunological side effects of antibiotics in man, i.e. under clinical conditions.

Influence of six antifungal agents on the chemiluminescence response of mouse spleen cells

The luminol-enhanced chemiluminescence (CL) assay is a measure of the early events of phagocytosis, leukocyte activation, and immune cell interactions. Reduction in the CL response of immune cells may be indicative of an inhibition of the immune response. This study was undertaken to examine the effects of antifungal agents tested at concentrations above and below therapeutically achievable levels on the CL response of mouse spleen cells. The effects of six antifungal agents--amphotericin B, ketoconazole, miconazole, 5-fluorocytosine, Bay-n-7133, and ICI 153,066--were studied. Changes in the CL response were assessed in terms of peak intensity and area under the intensity-time curve compared with appropriate diluent controls for each drug. Only amphotericin B and ketoconazole caused statistically significant lowering of the peak intensity at levels that are therapeutically attainable (mean peak plasma levels of 2 to 4 and 3.5 to 16 micrograms/ml, respectively). Although amphotericin B and ketoconazole caused reduction in the CL response, removal of the unbound drug in the preparation by centrifugation, washing, and suspension of cells in fresh drug-free medium resulted in a return of CL activity equivalent to the activity observed in cells not exposed to these agents. These results suggest that amphotericin B and ketoconazole at therapeutic concentrations may cause a reduction in immune cell antimicrobial activity; the clinical significance of these observations remains to be determined.