Vascular hyperpermeability induced by tumor necrosis factor and its augmentation by IL-1 and IFN-gamma is inhibited by selective depletion of neutrophils with a monoclonal antibody

We investigated whether various recombinant cytokines induce vascular hyperpermeability when intradermally injected into rats. Only TNF did so. Of the other cytokines examined (IL-1, IL-2, granulocyte-CSF, IFN-alpha, IFN-beta, IFN-gamma) none had this effect. The increase in vascular permeability was dose dependent, and the peak response was observed at 90 min after TNF injection. When mixtures of TNF and various other cytokines (IL-1, IL-2, granulocyte-CSF, IFN-alpha, IFN-beta, IFN-gamma) were injected, only IL-1 and IFN-gamma augmented TNF-induced vascular hyperpermeability, the increase occurring in a dose-dependent manner. The induction of vascular hyperpermeability by TNF and its enhancement by IL-1 and IFN-gamma were inhibited by selective depletion of peripheral blood neutrophils with i.p. administration of an anti-rat neutrophil mAb, RP-3. Reconstitution of neutrophils to the depleted rats by in situ injection of these cells, restored TNF increased vascular permeability.     

Reduced Anti-Pseudomonas aeruginosa Activity of a Cephalosporin,Cefodizime, in Rats Whose Neutrophils Were Selectively Depleted by a Monoclonal Antibody

In order to clarify the mechanisms of the in vivo antibacterial activity of a cephalosporin, cefodizime (CDZM), the effect of this antibiotic on Pseudomonas aeruginosa E7 infection was examined in rats whose neutrophils had been selectively depleted by monoclonal antibody RP-3. CDZM was less effective in RP-3-treated rats than in untreated rats. However, treatment of rats with recombinant human granulocyte-colony stimulating factor (rhG-CSF) augmented the in vivo activity of this antibiotic. Furthermore, the in vivo antibacterial activity of two other cephalosporins, cefpimizole (CPIZ) and cefoperazone (CPZ), was bilaterally affected by a rise or fall in the neutrophil number, although to a lesser degree than was the case with CDZM. Taken together, neutrophils play an important role in the in vivo antibacterial activity of certain cephalosporins.     

IgG antibodies to asialoGM1 are more sensitive than IgM antibodies to kill in vivo natural killer cells and prematured cytotoxic T lymphocytes of mouse spleen

IgG and IgM antibodies, which were isolated from the anti-asialoGM1 (GA1) serum, had different effects against natural killer (NK) and prematured cytotoxic T cells (CTLs) in in vivo administration and in in vitro treatment. In in vitro treatments, the IgM antibody killed NK cells of nude mouse spleen in the presence of complement (C') 12 times more potently than the IgG antibody did, and either antibody with C' killed pre-CTL. In in vivo administrations, only the IgG antibody was effective in diminishing NK activity of the nude mouse spleen cells and in suppressing antigen-specific CTL induction from primed spleen cells by in vitro stimulation with X-irradiated tumor cells. The IgM antibody was not effective at all in either system. The in vivo effect of the IgG on NK activity was blocked by preadministration with silica or carrageenan but not by that with cobra venom factor (CVF). These results indicate that in vivo administration of anti-GA1 antiserum leads to macrophage-mediated depletion of CTL precursors as well as NK cells.     

Priming activity for chemiluminescence reaction of PMN in the culture supernatant of streptococcal preparation (OK-432)-stimulated spleen cells

We investigated the effect of supernatant from human spleen cell culture stimulated with a streptococcal preparation, OK-432 (OK sup), on the luminol-dependent chemiluminescence (CL) of human polymorphonuclear leukocytes (PMN). The fMLP-stimulated CL of PMN was markedly enhanced by the pretreatment with OK sup. This result indicates that OK sup contained the factor(s) that primes fMLP-stimulated CL of PMN. The priming factor(s) in OK sup was partially inactivated by the treatment at 56 C for 30 min and pH 2 or pH 10 treatments. Since the enhancing effect of OK sup on the CL was inhibited by the treatment of sodium azide and the addition of catalase or taurine, it was assumed that OK sup augments the activity of MPO-H2O2-HOCl system of fMLP-stimulated PMN.     

Inhibition by Bacterial Lipopolysaccharide of Spontaneous and TNF-α-Induced Human Neutrophil Apoptosis In Vitro

In the previous paper (Takeda et al, Int. Immunol., 5, 691-694, 1993), we demonstrated that tumor necrosis factor-α (TNF-α) promptly accelerates apoptosis of human neutrophils in vitro. In order to determine the role of neutrophil apoptosis in defending against bacterial infection, we studied the effect of bacterial lipopolysaccharide (LPS) on this process. LPS inhibited spontaneous and TNF-α-induced human neutrophil apoptosis in vitro, as determined by 1) light and electron microscopy, 2) flow cytometry, and 3) agarose gel electrophoresis of DNA. Low concentrations of cycloheximide, a protein synthesis inhibitor, which alone did not affect neutrophil apoptosis, were able to reduce spontaneous apoptosis inhibition by LPS, suggesting the involvement of newly synthesized protein in this phenomenon.