Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was undertaken to define the effect of Legionella pneumophila protease on natural killer (NK) cell function in vitro. Lysis of target cells by human NK cells was determined using a 51Cr-release assay. The protease inhibited the NK cell cytolytic activity in a concentration- and time-dependent manner. The inhibitory effect of the protease was not affected by alpha interferon or interleukin 2. Legionella pneumophila protease partly inhibited the binding of effector cells to target cells as studied in a single cell agarose assay of monocyte-depleted cell populations. This effect of the protease on the binding of NK cells to target cells could interfere with the previously described enhanced NK cell activity induced by Legionella pneumophila. We could demonstrate in vitro inhibition of NK cell activity by Legionella pneumophila protease at very low concentrations, suggesting a possible relevance of this mechanism in the pathogenesis of Legionnaires' disease.
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PMID:Inhibition of human natural killer cell activity by Legionella pneumophila protease. 251 1

To determine if murine lymphocytes activated by interleukin 2 (IL-2) were cytotoxic against syngeneic elicited peritoneal macrophages (M phi) infected with intracellular pathogens, splenocytes that had been cultured with IL-2 for 5 or 10 days were studied in vitro. These cells, [lymphokine-activated killer (LAK) cells] showed significantly greater cytotoxicity against M phi infected with Leishmania major or Legionella pneumophila than against uninfected M phi. Preferential cytotoxicity against infected M phi was best shown using effector-to-target-cell ratios of 1:1-20:1; when ratios greater than or equal to 40:1 were employed, uninfected M phi were also lysed. The extent to which M phi that had been incubated with L. major were lysed depended upon the proportion of M phi containing intracellular organisms. After infection with L. major, the duration of incubation did not appear to influence the degree of lysis by LAK cells.
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PMID:Lysis of murine macrophages infected with intracellular pathogens by interleukin 2-activated killer (LAK) cells in vitro. 325 66