Acquired resistance of Escherichia coli to complement lysis by binding of glycophosphoinositol-anchored protectin (CD59)

Rautemaa-Richardson Richardson, Gary A. Jarvis, Pertti Marnila, Seppo Meri

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Protectin (CD59) is a glycophosphoinsitol (GPI)-anchored defender of human cells against lysis by the membrane attack complex of complement. In this study, we examined whether protectin released from human cell membranes can incorporate into the surface of gram-negative bacteria. Analysis by using radiolabeled protectin, immunofluorescence, flow cytometry, and whole-cell enzyme-linked immunosorbent assay demonstrated that protectin bound to nonencapsulated Escherichia coil EH237 (Re) and EH234 (Ra) in a calcium- dependent manner. The incorporation required the GPI-phospholipid moiety since no binding of a phospholipid-free soluble form of protectin was observed. Mg2+ did not enhance the binding, and a polysialic acid capsule prevented it (strain IH3080 [O18:K1:H8]). Bound protectin inhibited the C5b- 9 neoantigen expression on complement-treated bacteria. Protection against complement lysis was observed in both a colony counting assay and a bioluminescence assay, where viable EH234 bacteria expressing the luciferase gene emitted green light in the presence of the luciferine substrate. In general, two- to four-times-higher serum concentrations were needed to obtain 50% lysis of protectin-coated versus noncoated bacteria. The results indicate that protectin can incorporate in a functionally active form into the cell membranes of the two nonencapsulated deep rough E. coli strains studied.
    Original languageEnglish
    Pages (from-to)1928-1933
    Number of pages5
    JournalInfection and immunity
    Volume66
    Issue number5
    Publication statusPublished - May 1998

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