Scientists have discovered that eczema patients who have suffered an outbreak of eczema herpeticum possess a subset of T cells that appear to be less effective at fighting viruses than T cells in the rest of the population. The results, published online in the British Journal of Dermatology, may point to an impaired arm of the immune system, a weakness that enables the herpes simplex virus (HSV), the agent of eczema herpeticum, to thrive.
Eczema herpeticum (EH) is a nasty skin infection caused by the HSV. The researchers, led by Donald Leung at National Jewish Health in Denver, took T cells (specifically, the class of T cells that fights viral infection) from 24 eczema patients who had experienced EH. The scientists analyzed various aspects of the T cells, comparing them to T cells taken from control patients—with and without eczema—who had not been infected by HSV. The scientists found that T cells from the EH group were producing less of a signaling molecule called “interferon-gamma” than those from the control groups.
Interferon-gamma is known to play many important roles in the immune response, especially in fighting viral infections.
The researchers also tested the DNA of the patients and found that the EH group were statistically more likely to possess copies of genes encoding “HLA B7” proteins, which hold chopped-up viral fragments on the cell membrane as markers so that T cells can identify and destroy infected cells.
It seems clear to me that a lack of interferon-gamma might be a liability against viruses. (I wouldn't expect this deficiency to be an effect of EH infection rather than a contributing cause, but the authors don't discuss the possibility.)
Owning a copy of HLA B7 might seem to improve your ability to fight infection--especially since that group of proteins have been shown to present fragments of vaccinia virus. However, as Leung pointed out to me in an email, having HLA B7 didn't prevent many of the patients in this study from getting eczema herpeticum.
These results don't have any immediate application to helping patients, but the area they highlight might prove important in protecting patients from eczema herpeticum in the future.
This is the first paper I have seen that acknowledges funding by the Atopic Dermatitis Research Network. I am sure there are many more papers out there, but this is the first I have noticed since the inception of the $31 million program, founded in 2010 to explore skin infections related to eczema.