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Infect. Immun., Jun 1995, 2248-2254, Vol 63, No. 6
JM Klapproth, MS Donnenberg, JM Abraham, HL Mobley and SP James
The aim of this study was to determine whether products of enteric bacteria
are able to regulate lymphocyte activation and cytokine production. Whole
bacteria and bacterial lysates from different strains of Escherichia coli
were tested for their ability to inhibit cytokine production by peripheral
blood mononuclear cells as determined by reverse transcription-PCR,
Northern (RNA) blotting of cellular RNA, or enzyme-linked immunosorbent
assay for cytokine protein. Lysates from two pathogenic strains of E. coli,
enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli, inhibited
mitogen-stimulated expression of interleukin-2 (IL-2), IL-4, IL-5, and
gamma interferon. IL-1 beta, IL- 6, IL-8, IL-10, IL-12, and Rantes mRNA
expression was not affected. The inhibitory activity was dose dependent,
protease and heat sensitive, nondialyzable, and not due to cellular
toxicity. The inhibitory activity remained in EPEC strains having mutations
in known virulence factors. Nonpathogenic E. coli HB101 transformed with a
22-kb cosmid clone derived from EPEC chromosomal DNA expressed the
inhibitory activity. Thus, certain strains of pathogenic E. coli express a
protein or proteins encoded by chromosomal genes that selectively inhibit
lymphocyte activation and lymphokine production. Therefore,
immunosuppressive factors produced by pathogenic bacteria could be
important in modifying gastrointestinal immune responses in enteric
bacterial infections or gastrointestinal autoimmune diseases.
Copyright © 1995, American Society for Microbiology
Products of enteropathogenic Escherichia coli inhibit lymphocyte activation and lymphokine production
Division of Gastroenterology, University of Maryland at Baltimore 21201- 1595, USA.
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