Role of macrophage cytokines in influenza A virus infections.

Human monocytes and murine macrophages were found to be susceptible to infection by influenza A virus. Although virus replication was low, infection led to cell death which was characterized by an extreme intracellular vacuolization. Most importantly, influenza A virus infection was accompanied by a particular pattern of cytokine release. Whereas IL-1 beta, IL-6 and TNF-alpha production was dependent on exposure to infectious virus, IFN-alpha/beta release was also induced by UV-inactivated virus. Although influenza A virus infection alone induced a substantial cytokine mRNA accumulation, translation into bioactive cytokine protein was rather limited. However, addition of low LPS concentrations was capable of strongly potentiating cytokine release from virus-infected cells. Thus, in a first step, an influenza A virus infection primes mononuclear phagocytes by leading to an accumulation of cytokine mRNA which, in a second step, may be readily translated into bioactive cytokines when triggering signals such as LPS are available. These findings suggest that influenza A virus represents an ultimately fatal macrophage activating factor which, when inducing moderate amounts of cytokines, may be beneficial by mounting an immediate antiviral response, but which may cause adverse effects when cytokine release is highly elevated by bacterial products.

Effect of cis-diaminedichloroplatinum (II) (cis-DDP) on the intracellular Na+/K(+)-ratio in K 562 leukemia cells as revealed by X-ray microanalysis.

Changes of intracellular ionic homeostasis are believed to play a role in the cytostatic action of cis-DDP. It has been observed by means of X-ray microanalysis that cis-DDP did not alter the intracellular Na+/K(+)-ratio of K 562 leukemia cells during incubation periods which lasted shorter than the average doubling time of the cells of nearly 15 h. After 24 h the treated cells displayed at least two main populations in the distribution histogram of the Na+/K(+)-ratio. The results indicated that the passage of cis-DDP through the plasma membrane by itself did not change the monovalent electrolyte balance at the early stage of its action in K 562 cells.

In vivo changes of heterogeneity of mouse peritoneal macrophages induced by cis-diamminedichloroplatinum (II) (cis-DDP) and related platinum compounds.

The s.c. injection of cis-DDP into ABD2F1 mice (8 mg/kg b.m.) resulted in alterations of size and surface structure of peritoneal macrophages (PM) and in a reduction of the mean number of Concanavalin A (ConA) binding sites of PM. The PM population of control mice which received physiological saline only consisted of 2 subgroups with a higher and a lower mean ConA binding site number per cell. Contrarily, PM of cis-DDP-treated mice failed the subpopulation with higher ConA binding site number. A loss of this subpopulation was also found in mice treated with platinum salt K2PtCl4 or K2PtCl6. X-ray microanalytically determined elemental contents of PM of control and treated mice showed a correlation between ConA binding site number and cellular concentration of phosphorus or sulphur with the exception of a small group of PM which was characterized by a high content of sulphur and a low number of ConA binding site. This correlation was not found in normal mice.

Bestatin-induced enhancement of in vivo phagocytosis determined by a new simple assay.

Pretreatment of mice by the immunostimulator bestatin resulted after four days in a significant enhancement of the phagocytic activity of peritoneal cells. For quantification of the phagocytic process of murine peritoneal phagocytes a new in vivo assay is proposed. Fluorescein isothiocyanate (FITC)-labeled Escherichia coli bacteria were i.p. injected. After ten minutes peritoneal cells were harvested and the phagocytic index of peritoneal phagocytes was fluorescence-photometrically assessed. The frequency distribution of phagocytized bacteria per cell found by the this assay corresponded to Poisson distribution. This coincidence allowed estimation of the minimum number of cells needed for detecting a significant difference of phagocytosis indices, resulting in an enhancement of test efficiency.

Effect of different fixatives on Con A surface receptors of mouse peritoneal macrophages.

The effects of glutaraldehyde, formaldehyde, or osmium tetroxide fixation on the number of labeled Con A surface receptors on mouse peritoneal macrophages were compared. Gold-labeled Con A receptors were found to be isolatedly arranged and evenly distributed on cell surfaces independent of the fixative used. Only cells preincubated with Con A and subsequently fixed by osmium tetroxide showed arrangement of labeled receptors in clusters. Significant differences were found in the number of Con A receptors per cell depending on the fixative used. The fluorescence intensity of FITC-Con A staining was detected spectrophotometrically, the characteristic X-rays of gold-labeled Con A receptors were determined by means of electron beam-induced X-ray microanalysis. The experimental results obtained both at light and electron microscopic level pointed to formaldehyde being the best fixative also for this purpose.

Is the proliferation inhibition of K562 cells by cisplatin also a membrane effect?

Using K562 tumour cells as model, the effect of cisplatin on cellular morphology and electrolyte balance was examined by scanning electron microscopy and energy-dispersive X-ray microanalysis. The data imply that the membrane surface alterations are a secondary effect following cross-linking reaction of this drug with DNA.

Low voltage SEM--prospects and limits in biological research.

Low voltage SEM shows, in general, topographic and compositional contrast of nonconducting beam-sensitive specimens by secondary electrons without coating. But until now imaging of small surface features rich in contrast requires metal-coating.

Determination of gold-labelled surface receptors on single cells by X-ray microanalysis.

A standardless X-ray microanalytical procedure has been developed to determine the number of gold-labelled surface receptors on whole single cells. The effect of the injection of K2PtCl4 into mice on gold-labelled concanavalin A (Con A) receptors on peritoneal macrophages was examined with an energy dispersive X-ray detector in an SEM. The numbers of gold particles seen in electron micrographs and estimated by fluorescence photometric measurements of fluorescein isothiocyanate-labelled Con A receptors were correlated with the X-ray microanalytical results.

Effect of several fixatives on the density of concanavalin A binding sites of murine peritoneal macrophages determined by fluorescence microscopy and X-ray microanalysis.

The influence of various fixatives (glutaraldehyde, formaldehyde, OsO4) on the retention of antigenicity of peritoneal macrophages was studied by means of fluorescence microscopy, scanning electron microscopy, and X-ray microanalysis. After fixation with formaldehyde the Concanavalin A (Con A) binding sites were found to be highest, whereas the fixation with OsO4 results in loss of many binding sites. The fluorescence microscopic investigations of glutaraldehyde fixed cells is impaired by fixative induced fluorescence. Therefore X-ray microanalytical determinations show better results for these cells than fluorescence microscopic measurements. On contrary to direct labelling method the number of unspecific Con A binding sites on peritoneal macrophages labelled with the sandwich method is negligible.

Effects of antifertility estrogens and progestins on the endometrial surface of early pregnant rats. A scanning electron microscopic study.

Two estrogens, mestranol and 3-methoxy-14 beta, 15 beta-methyleneestra-1,3,5(10)triene-17 beta-ol (STS 593), and two progestins, levonorgestrel and 17 alpha-cyanomethyl-17 beta-hydroxyestra-4,9(10)-diene-3-one (STS 557), all having antifertility properties in rodents, were examined for their effects on the uterine luminal surface of early pregnant rats. Scanning electron microscopic studies showed that there are clear qualitative differences between the effects of estrogens and progestins on both morphology and microvillous pattern of the endometrial surface while STS 557 showed intermediate effects. The results are discussed with respect to the anti-implantation activity of steroids.

Effect of potential cytostatic and immune modulating chemicals on the plasma membrane of red blood cells (RBC) as revealed by osmotic hemolysis, cell electrophoresis and scanning electron microscopy (SEM).

The influence on red blood cells (RBC) of two cancerostatic-(ZIMET 3106 and ZIMET 3393) and two immunomodulating agents (ZIMET 3164 and ZIMET 86/76) administered subcutaneously, or intraperitoneally in case of the radiolabelled N-mustard compounds, to mice, was studied by means of measurements of the radiolabelled compounds in blood, by cell electrophoresis, filipin-induced hemolysis of pretreated RBC and by scanning electronmicroscopy. The portion of doses applied which binds to RBC-surface decreases in the sequence of ZIMET 3106, ZIMET 3164, ZIMET 3393 and ZIMET 86/76. However, the highest reduction of the electrophoretic mobility and protection from filipin-induced hemolysis of pretreated RBC was found with ZIMET 3164. In both tests ZIMET 86/76 proved to be ineffective. These findings are in good agreement with the modifications demonstrated in pretreated RBC after filipin-induced hemolysis by means of SEM. The results presented point to a N-mustard specific interaction between the cholesterol of the membrane and/or other membrane constituents. However, these fundamental differences found in binding affinity, surface-charges and membrane interactions caused by the chemically similar compounds cannot be attributed merely to the N-mustard group.