We’re Revealing Clues about the Immune System

(From the February 2013 issue of Inside Nationwide Children's)

Recent Nationwide Children’s studies of critically ill children are revealing important clues about the body’s immune response.

One study, conducted by Asuncion Mejias, MD, PhD; Octavio Ramilo, MD; Mark Hall, MD, and colleagues, was published in the December issue of the Journal of Infectious Diseases. It suggests for children with RSV infection, a weakened immune response correlates with more severe forms of the disease.

A second study led by Dr. Hall and recently published in the journal, Critical Care Medicine, showed a similar effect among critically ill children with influenza.

The body’s innate immune system serves as a first-responder to new threats, and is thought to drive the inflammatory response in many forms of critical illness.  Traditional theories suggest critically ill children with infections would have an excessive immune response. However, recent evidence shows just the opposite, the immune response is suppressed.

Results from both studies indicate that monitoring a critically ill child’s immune function could have important clinical implications, such as the use of drugs that stimulate the immune system, changing the way these patients typically have been treated.

THE STUDIES AT A GLANCE

Study involving patients with RSV:

• Team evaluated 66 previously-healthy children less than two years old and hospitalized with a first episode of RSV bronchiolitis
• Found critically ill children with RSV admitted to PICU had significantly weakened immune system function compared with healthy children and infants with less severe RSV bronchiolitis hospitalized in the Infectious Diseases unit.

Study involving patients with influenza:

• Investigators from 15 children’s medical centers observed and evaluated 52 critically ill children ages 18 or younger with influenza
• Found critically ill patients with influenza had significantly weakened immune system function compared with healthy children
• Patients co-infected with influenza and the bacteria S. aureus showed the greatest degree of immune suppression

Mella C, Suarez-Arrabal MC, Lopez S, Stephens J, Fernandez S, Hall MW, Ramilo O, Mejias A. “Innate Immune Dysfunction is Associated with Enhanced Disease Severity In Infants with Severe Respiratory Syncytial Virus Bronchiolitis.” Journal of Infectious Diseases. 2012 Dec 27. [Epub ahead of print]

Hall MW, Geyer SM, Guo CY, Panoskaltsis-Mortari A, Jouvet P, Ferdinands J, Shay DK, Nateri J, Greathouse K, Sullivan R, Tran T, Keisling S, Randolph AG; Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network PICFlu Study Investigators. “Innate Immune Function and Mortality in Critically Ill Children With Influenza: A Multicenter Study” Critical Care Medicine. 2013 Jan;41(1):224-236.