The bystander effect in optically trapped red blood cells due to plasmodium falciparum infection

Apurba Paul, Rani Pallavi, Utpal S. Tatu, Vasant Natarajan

Research output: Contribution to journalArticle


Background: In a previous study of the properties of red blood cells (RBC) trapped in an optical tweezers trap, an increase in the spectrum of Brownian fluctuations for RBCs from a Plasmodium falciparum culture (due to increased rigidity) compared with normal RBCs was measured. A bystander effect was observed, whereby RBCs actually hosting the parasite had an effect on the physical properties of remaining non-hosting RBCs. Methods: The distribution of corner frequency (fc) in the power spectrum of single RBCs held in an optical tweezers trap was studied. Two tests were done to confirm the bystander effect. In the first, RBCs from an infected culture were separated into hosting and non-hosting RBCs. In the second, all RBCs were removed from the infected culture, and normal RBCs were incubated in the spent medium. The trapping environment was the same for all measurements so only changes in the properties of RBCs were measured. Results: In the first experiment, a similar and statistically significant increase was measured both for hosting and non-hosting RBCs. In the second experiment, normal RBCs incubated in spent medium started to become rigid after a few hours and showed complete changes (comparable with RBCs from the infected culture) after 24 h. Conclusion: These experiments provide direct evidence of medium-induced changes in the properties of RBCs in an infected culture, regardless of whether the RBCs actually host the parasite.

Original languageEnglish
Pages (from-to)220-223
Number of pages4
JournalTransactions of the Royal Society of Tropical Medicine and Hygiene
Issue number4
Publication statusPublished - Apr 2013


  • Bystander effect
  • Malaria
  • Malaria culture
  • Optical tweezers
  • Plasmodium falciparum
  • Red blood cells

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases
  • Public Health, Environmental and Occupational Health

Fingerprint Dive into the research topics of 'The bystander effect in optically trapped red blood cells due to plasmodium falciparum infection'. Together they form a unique fingerprint.

  • Cite this