Mystery of potentially fatal reaction to smallpox vaccine unraveled

Washington, May 25 (ANI): A husband-wife scientific team from the La Jolla Institute for Allergy and Immunology have identified the cellular defect that makes eczema sufferers more prone to eczema vaccinatum, a severe and potentially fatal reaction to the smallpox vaccine.

Doctors Toshiaki and Yuko Kawakami have found that activity levels of Natural Killer (NK) cells, which are disease fighting cells of the immune system, play a pivotal role in the development of eczema vaccinatum in the mice.

The researchers found that the activity of the NK cells was significantly lower in the mice that developed eczema vaccinatum than in normal mice that also received the smallpox vaccine.

They say that this knowledge opens the door to one day developing therapies that could potentially boost NK cell activity in eczema sufferers.

"Since atopic dermatitis affects as many as 17 percent of children in the U. S. and since eczema vaccinatum carries a fatality rate of 5-10 percent, therapies that prevent or treat eczema vaccinatum successfully are crucial should the need for mass vaccination against smallpox arise in response to bioterrorism," said Harvard pediatrics professor Dr. Raif S. Geha, of immunology at Boston Children's Hospital and a principal investigator in the NIH funded network investigating eczema vaccinatum.

"The discovery of the Kawakami team, who are participants in the NIH network, is an important step towards this goal," Geha added.

People with active atopic dermatitis (eczema), or who have outgrown it, and those with whom they currently live cannot receive smallpox vaccinations because of the risk of eczema vaccinatum.

While uncommon, eczema vaccinatum can develop when atopic dermatitis patients are given the smallpox vaccine or come into close personal contact with people who recently received the vaccine.

A significant portion of the U.S. population is currently considered to be ineligible for smallpox vaccination.

"This discovery answers an important question that has long eluded the scientific community, why people with atopic dermatitis were susceptible to developing eczema vaccinatum upon receiving the smallpox vaccine, while the general population was not. It marks a significant advance toward the goal of ensuring that everyone can one day be protected against the smallpox virus," said Mitchell Kronenberg, the La Jolla Institute's president and scientific director.

Toshiaki Kawakami said: "We are very excited by these findings. Developing a safer smallpox vaccine is the most important thing in this field."

A research paper on the study has been published in the online version of the Journal of Experimental Medicine. (ANI)