Effect of 24 antimicrobial drugs on polymorphonuclear leukocyte adherence

Role of lipopolysaccharide in signaling to subepithelial polymorphonuclear leukocytes

Polymorphonuclear leukocyte (PMN) infiltration and migration across colonic intestinal epithelia is a hallmark of inflammation in Shigella flexneri-mediated dysentery. To identify bacterial signals associated with this process, potential stimulatory factors mediating initial PMN association with the epithelium and subsequent transepithelial migration were examined in an in vitro model system. Quantitative analyses revealed that purified S. flexneri lipopolysaccharide (LPS) deposited at the apical surface of polarized intestinal epithelial cells transcytosed to the basolateral pole, a process dependent on the stage of epithelial cell differentiation. Transcytosed LPS in the presence of normal human serum (NHS), a source of LPS binding protein and soluble CD14, mediated both interleukin-8 secretion at the basolateral pole and enhanced PMN adherence. In addition, LPS stimulated a significant degree of directed transepithelial migration of PMNs, an event that was further enhanced in the presence of NHS. These results implicate LPS in signaling subepithelial PMN emigration and enhancing PMN-epithelium interactions prior to and during subsequent Shigella-induced transepithelial migration.

Cytoprotection against neutrophil-delivered oxidant attack by antibiotics

In the present study we have investigated the effect of six antibiotics (penicillin G, ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin) on the neutrophil cytolytic activity by using a system constituted of phorbol-12-myristate-13-acetate-triggered neutrophils and 51Cr-labelled lymphoblastoid Daudi target cells. The results demonstrate that five of these drugs (ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin) are capable of inhibiting the neutrophil cytolytic activity by inactivating the hypochlorous acid (HOCl) generated extracellularly by the myeloperoxidase pathway and crucial to the target cell lysis. Penicillin G had no effect on neutrophil-mediated cytolysis. Thus, these data demonstrate that ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin lower the neutrophil-mediated target cell damage by a HOCl-scavenging mechanism, suggesting a possible cytoprotective role for these drugs during infections.

Suppression of neutrophil and lymphoproliferative responses in vitro by itraconazole but not fluconazole

Itraconazole and fluconazole are triazole compounds recently licensed for the therapy of systemic fungal infections. At 10 micrograms/ml concentrations, itraconazole was found to suppress neutrophil chemotaxis, random movement, deoxyglucose uptake and hexose-monophosphate shunt activity to the same extent as ketoconazole, an older generation azole antifungal. Itraconazole was also found to suppress mitogen-induced lymphocyte transformation to the same extent as ketoconazole at concentrations as low as 1 microgram/ml. By contrast, significant inhibition of both neutrophil and lymphocyte functions was not observed with fluconazole at concentrations as high as 50 micrograms/ml. These results suggest that fluconazole may be less immunotoxic than itraconazole, and may be more suitable for use in immunocompromised patients.

Effect of Salmonella typhimurium porins on biological activities of human polymorphonuclear leukocytes

The effect of Salmonella typhimurium porins on human polymorphonuclear leukocytes (PMNs) was studied. Labeled porins were shown to bind to the PMNs, and could be completely displaced by unlabeled porins. The binding caused modifications of membrane integrity and of the physico-chemical characteristics of the PMN surface, e.g. decreased oxidative burst, decreased hydrophobicity and altered cell morphology. The porins acted as both chemotaxins and chemotaxinogens. When PMNs were preincubated with porins their migration in the presence of commonly used chemoattractants (serum activated by zymosan or N-formyl-L-methionyl-L-leucyl-L-phenylalanine) was inhibited.

Effect of vitamin K3 on macrophage functions and intracellular calcium

1. The effect of vitamin(vit) K3 on guinea-pig macrophage functions was studied. 2. Vit K3 inhibited macrophage locomotion, phagocytosis and lysosomal enzyme release. 3. Vit K3 inhibited the rise in the intracellular free calcium level induced by stimuli at the concentration at which vit K3 suppressed functions. 4. These results suggest that vit K3 inhibits macrophage functions through the interference with the mobilization of intracellular calcium.

The effects of in vivo antibiotics on neutrophil (PMN) activity in rabbits with peritonitis

Antibiotics play an important role in helping the host fight infection; however, the direct cellular effect of antibiotics on polymorphonuclear cells remains undefined. Adherence, chemotaxis, phagocytosis, and superoxide anion production are important steps in the cascade of events initiated by the polymorphonucleocyte in bacterial killing. Previous studies have shown inhibition as well as stimulation of neutrophil antibacterial therapy by antibiotics. Peritoneal and blood polymorphonuclear neutrophils (PMN) respond differently to peritonitis and to external agents. The purpose of this study was to investigate the effects of in vivo clindamycin and netilmicin on infected rabbit peritoneal and blood polymorphonuclear adhesiveness, phagocytosis, chemotaxis, and superoxide anion production. Peritoneal and blood PMNs were obtained from rabbits which had undergone appendiceal devascularization 18 hr earlier: antibiotics were administered intramuscularly 1 hr prior to appendectomy and every 8 hr postoperatively for 5 days; these PMNs were compared to infected rabbits which did not receive antibiotics. Clindamycin and netilmicin in vivo cause significant inhibition of phagocytosis, peritoneal adhesiveness, and, when used in combination, blood adhesiveness and peritoneal superoxide anion production. No effects were seen on chemotaxis. Based on this data we conclude that antibiotics, while vitally important in fighting infections, may in and of themselves be agents of immunosuppression at the cellular level.

Doxycycline effects on the adherence of polymorphonuclear leukocytes to an albumin-coated glass surface

The effect of doxycycline on polymorphonuclear leukocyte (PMN) adherence to albumin-coated glass surfaces was studied in the absence and presence of the chemotactic peptide FMLP. Three concentrations of doxycycline were studied, one subtherapeutic (0.1 micrograms/ml), one therapeutic (1.0 micrograms/ml) and one supertherapeutic (10 micrograms/ml). PMN adherence was maximal after incubation for 5 min. FMLP did not affect PMN adherence in the present assay system and at the concentration studied (10(-7)M). PMN adherence remained stable and unaffected in the tested doxycycline concentrations. Thus, the present study could not confirm the reported and challenged doxycycline inhibition of PMN adherence.