Usually seen in ICU patients battling severe sepsis, the cytokine storm occurs when the body mounts a hyper-reactive immune response so massive it harms itself, sometimes fatally.
It's the biological equivalent of friendly fire.
Immune System Overdrive
Because they have stronger immune systems than the elderly or infants, young adults "could be most poised to produce a cytokine storm," said Kathleen Sullivan, MD, PhD, chief of the Division of Allergy and Immunology at The Children's Hospital of Philadelphia.
The cytokine storm "refers to a state where all guns are firing in a non-organ-specific fashion," she said. "Instead of appropriately directing the immune system to a given target, the process goes into overdrive. When the immune system is attacking on all fronts, it is deleterious."
Cytokines "are chemical messengers produced by white blood cells and tissue cells that regulate the inflammatory response and immunity," said Kenneley, who is an assistant professor at Case Western Reserve University Frances Payne Bolton School of Nursing in Cleveland.
"A cytokine storm occurs when the body's immune system overreacts to an intruder, such as a virus, by producing high levels of cytokines," Kenneley explained. "When too many cytokines are produced, they can stimulate an inflammatory response in which the accumulation of immune cells and fluid at the site of infection may prevent affected tissues and organs such as the lungs from functioning properly and may even cause death due to severe damage and fluid buildup in the lungs themselves."
The relative youth of swine flu casualties bears a disquieting similarity to deaths from the infamous 1918 influenza A H1N1 pandemic. Nearly half of those approximately 50 million casualties were young adults 20 to 40 years old, Kenneley said; although we still don't know what factors may have fueled the 1918 pandemic's engine of death.
Depressed Response
In an article published online March 10 in the Journal of Leukocyte Biology, Sullivan and colleagues demonstrated swine flu patients may indeed be at risk of a paralyzed immune system, leading to potentially fatal secondary infections - but for a different reason than the cytokine storm.
Sullivan et al. recruited pediatric patients with severe influenza and compared their pathology with that of five patients with moderate influenza, six with respiratory syncytial virus, and 24 with no health problems who served as controls.
They found elevated levels of cytokines in the severe influenza group, but also a depressed response to toll-like receptor (TLR) ligands, which activate the body's immune cell responses so it attacks invading microbes. Aberrant responses to TLR ligands "may underlie the known susceptibility of influenza-infected patients to secondary bacterial infections," the researchers concluded.
Reactions to her finding so far "have ranged from pleased to surprised," Sullivan told ADVANCE.
The study by Sullivan et al. "brings us a step closer to understanding exactly what goes wrong in some people who get swine flu, so, ultimately, physicians can develop more effective treatment strategies," John Wherry, PhD, deputy editor of the Journal of Leukocyte Biology, told Reuters.
SYMPTOMS OF THE CYTOKINE STORM:
The end stage, or final result, of cytokine storm (SIRS) or sepsis is multiple organ dysfunction syndrome (MODS). The end-stage symptoms of the bird flu, or other infection precipitating the cytokine storm may include:
- hypotension
- tachycardia
- dyspnea
- fever (temperature of >38°C or >100.4°F)
- Ischemia, or insufficient tissue perfusion (especially involving the major organs)
- uncontrollable hemorrhage
- and multisystem organ failure (caused primarily by hypoxia, tissue acidosis, and severe metabolism dysregulation
No comments:
Post a Comment