The iC3b receptor on Candida albicans: subcellular localization and modulation of receptor expression by glucose

J Infect Dis. 1990 Apr;161(4):761-8. doi: 10.1093/infdis/161.4.761.

Abstract

Patient isolates of Candida albicans from blood, urine, or mucosal sites express a surface receptor for C3 fragment iC3b that is recognized by monoclonal antibodies (MAb) directed against alpha-chain epitopes of the neutrophil iC3b receptor, also known as the type 3 complement receptor (CR3) or CD11b/CD18. Because 60% of these patients were hyperglycemic, the effect of glucose on receptor expression was investigated. As assessed by flow cytometry, yeasts grown in 20 mM D-glucose exhibited a four- to six-fold increase in receptor expression compared with yeasts grown in 20 mM L-glutamate. Receptor expression increased as glucose concentration rose from 0 to 20 mM (equivalent to plasma glucose concentrations of 0-360 mg/dl). Augmentation of receptor expression by growth in glucose led to significant inhibition of phagocytosis compared with that of organisms grown in equimolar L-glutamate. SDS-PAGE, Western blotting, and immunodetection of extracts of yeast cell wall, membrane, and cytosol disclosed a protein of 165 kDa in membrane and cytosolic extracts, consistent with the published Mr of the alpha-chain of neutrophil CR3. These studies provide a mechanism to explain the predilection of C. albicans to infect the hyperglycemic host.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Candida albicans / immunology
  • Candida albicans / metabolism*
  • Candidiasis / complications
  • Candidiasis / microbiology
  • Child
  • Child, Preschool
  • Complement C3b / metabolism*
  • Flow Cytometry
  • Glucose / pharmacology*
  • Humans
  • Hyperglycemia / complications
  • Hyperglycemia / microbiology
  • Infant
  • Middle Aged
  • Phagocytosis
  • Receptors, Complement / analysis*
  • Receptors, Complement / biosynthesis
  • Receptors, Complement / drug effects
  • Receptors, Complement 3b

Substances

  • Receptors, Complement
  • Receptors, Complement 3b
  • Complement C3b
  • Glucose