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Targeting proteins to secretory lysosomes of natural killer cells as a principle for immunoregulation

Markus Hansson1, Sofia Jönsson, Ann-Maj Persson

  • 1Department of Hematology, C14, BMC, SE-22184, Lund, Sweden. markus.hansson@hematologia.lu.se

Molecular Immunology
|October 3, 2003
PubMed

Insights

Researchers explored targeting proteins to natural killer (NK) cell secretory lysosomes for tumor delivery. They successfully engineered a soluble TNF receptor for lysosomal targeting and secretion upon NK cell degranulation.

Area of Science:

  • Immunology
  • Cell Biology
  • Biotechnology

Background:

  • Natural killer (NK) cells possess secretory lysosomes that store and release molecules.
  • Targeting therapeutic proteins to these secretory lysosomes could enable targeted delivery to tumor sites.

Purpose of the Study:

  • To investigate the feasibility of directing exogenous proteins to NK cell secretory lysosomes.
  • To explore the potential of NK cell secretory lysosomes as carriers for drug delivery to tumors.

Main Methods:

  • Engineered cDNA constructs for soluble and transmembrane proteins, including a modified soluble TNF receptor (sTNFR1).
  • Expressed constructs in the human YT-Indy NK cell line.
  • Utilized biosynthetic radiolabeling, subcellular fractionation, immunoelectron microscopy, and immunofluorescence microscopy for verification.

Main Results:

  • Successfully targeted a modified sTNFR1 (sTNFR1-tm-Y) to secretory lysosomes in NK cells.
  • Confirmed lysosomal localization and subsequent release of soluble sTNFR1 via endogenous proteolytic activity.
  • Observed mostly constitutive secretion for other exogenous proteins, with limited lysosomal targeting for alpha1-microglobulin.

Conclusions:

  • NK cell secretory lysosomes can be engineered to target and deliver exogenous proteins.
  • This approach holds potential for developing novel strategies for targeted drug delivery to tumor microenvironments.
  • Further research may optimize protein targeting for enhanced therapeutic efficacy.

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