The Use of Lysostaphin in in Vitro Assays of Phagocyte Function: Adherence to and Penetration into Granulocytes

The usefulness of lysostaphin for the removal of cell-adherent and extracellular bacteria in assays performed to measure the intracellular killing of Straphylococcus aureus by granulocytes was investigated. The results showed that the adherence of lysosiaphin to the granulocyte surface is effectuated by a temperature-independent process and that bound lysostaphin is still microbicidal. Lysosiaphin also penetrates into the granulocytes by a temperature dependent process and kills ingested S. aureus intracellularly. Therefore, despite reports to the contrary in the literature, lysosiaphin is not a reliable agent for the removal of only extracellular S. aureus and should no longer be used in assays to determine the rate of intracellular killing by granulocytes.     

Hydrocortisone Treatment of BCG-Infected Mice Impairs the Activation and Enhancement of Antimicrobial Activity of Peritoneal Macrophages

The present study concerns the effect of hydrocortisone (HC) on the effector functions of Bacillus Calmette Guerin-purified protein derivative (BCG-PPD)-activated macrophages. Such activated macrophages release greater amounts of H2O2 and NO2-, inhibit the intracellular proliferation of T. gondii and kill L. monocytogenes more efficiently than resident macrophages. This activation was not fully expressed by macrophages from BCG-activated mice that had received a subcutaneous injection of HC 2 days before intraperitoneal injection of PPD, since the inhibition of the intracellular proliferation of T. gondii, the release of NO2- and the rate of intracellular killing of L. monocytogenes were lower than in macrophages from BCG-PPD-activated mice. However, treatment with HC did not impair the release of H2O2 by BCG-PPD-activated macrophages. The results show that the treatment of infected mice with HC inhibits their ability to develop adequate intracellular microbicidal mechanisms.     

NORMAL MICROBICIDAL FUNCTION OF MONOCYTES IN A GIRL WITH CHRONIC GRANULOMATOUS DISEASE

ABSTRACT. Weemaes, C., (Department of Paediatrics, University Hospital, Nijmegen, The Netherlands), Leijh, P., Blusse van Oud Alblas, D., van der Meer, J. and van Furth, R. (Department of Infectious Diseases, University Hospital, Leiden, The Netherlands). Normal microbicidal function of monocytes in a girl with chronic granulomatous disease. Acta Paediatr Scand, 70:421, 1981.–The history of a 13-year-old girl with a syndrome resembling Chronic Granulomatous Disease (C.G.D.) is described. Metabolic studies in granulocytes and monocytes classified the patient as having C.G.D. The granulocytes failed to kill Staphylococcus aureus and Candida Albicans; however, the killing of these microorganisms by the patient's monocytes was nearly normal. Family studies revealed no abnormalities in the phagocytic cells of the parents and the siblings.     

Differences in the Rate of Intracellular Killing of Catalase-Negative and Catalase-Positive Listeria monocytogenes by Normal and Interferon-Gamma-Activated Macrophages

Intracellular killing of catalase-positive bacteria by murine resident macrophages requires the presence of extracellular serum, whereas killing of catalase-negative bacteria can occur in the absence of serum. To find out whether the intracellular killing of bacteria by rIFN-γ-activated macrophages also requires serum stimulation, we investigated the handling of ingested catalase-negative and -positive Listeria monocytogenes by peritoneal macrophages of normal Swiss mice and mice injected i. p. with I × 10⁴U rIFN-γ 18 h earlier. In the absence of extracellular serum. rlFN-γ-activated macrophages killed ingested catalase-negative Listeria more efficiently (P<0.01) than normal resident macrophages. Maximal killing of catalase-negative bacteria by rlFN-γ-activated macrophages required an extracellular serum concentration of only 1.0 to 2.5% compared with the 10% needed by normal macrophages. No differences were observed in the rates of intracellular killing of catalase-positive Listeria by rlFN-γ-activated and normal resident macrophages: both populations of macrophages required 10% extracellular serum for maximal killing of these bacteria, and killing was minimal in the absence of scrum. The rIFN-γ-activated macrophages displayed enhanced O₂-consumption after stimulation with phorbol myristate acetate and heat-killed Listeria compared with macrophages from normal mice. These findings indicate that, under suboptimal stimulation by extracellular serum. rlFN-γ enhances the intracellular killing of catalase-negative Listeria which lack endogenous catalase acting as a scavenger of reactive oxygen intermediates. The mechanism underlying the enhancement is probably the amplification of the respiratory burst by IFN-γ.