Immune cells implicated in fatal seizures in viral meningitis

December 26th, 2008 - 6:32 pm ICT by ANI  

London, Dec 26 (ANI): Researchers from New York University Langone Medical Centre claim to have uncovered the potential cause of fatal seizures in viral meningitis.

In a study on mice with viral meningitis, the researchers found that these seizures are not caused by the virus itself, but by the immune system’’s response to the infection.

During the study, the researchers injected the mice with lymphocytic choriomeningitis virus (LCMV), which is relatively harmless in humans with a healthy immune system.

The mice with LCMV suffered fatal seizures. With the help of intravital two-photon microscopy the researchers looked inside the skulls of infected mice and analysed the immune cells in action.

Something sets off a chain of events that begins with leakage of fluid from blood vessels into the meninges, the protective covering of the brain and spinal cord, followed by swelling, which in turn leads to seizures.

“T-cells, which are designed to attack the virus, were thought to be the bad guys, but no one understood the exact cellular dynamics involved in infection-induced seizures,” Nature magazine quoted Dr. Jiyun V. Kim, a scientist in Dr. Dustin’’s laboratory as saying.

The results showed that rather than attacking cells infected with the virus, the T-cells wandered around, apparently unable to recognize their targets.

“Up to a point, the T-cells did everything they should do,” said Dustin.

“They made copies of themselves and migrated to where the virus was, but when they got there, they couldn”t do the right thing. At least they didn”t do what we expected them to, which was to stick tightly to the infected cells.

“A series of frozen images gave the misleading impression that the T-cells were engaging with the infected cells, but intravital microscopy clearly showed that the immune cells appeared to overrun the infected cells”, Dustin added.

Further studies revealed that monocytes and neutrophils, two types of white blood cells that usually fight bacteria, not viruses are the real culprit behind the malfunctioning of immune system.

Intravital microscopy showed massive numbers of these white blood cells breaking through the walls of blood vessels into the meninges, opening the floodgates for fluid to pour out and cause swelling.

We”ve discovered a totally new targetthe neutrophils and monocytes recruited by the T-cells,” said Dustin.

“If you can prevent that recruitment process, either by inhibiting the T-cells or, preferably, inhibiting the monocytes and neutrophils, you can probably prevent the disease,” he added. (ANI)

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