By David Douglas
NEW YORK (Reuters Health) – There appears to be a relationship between the immune response to respiratory syncytial virus (RSV) attachment (G) protein and asthma severity, according to New York researchers.
Dr. Gerald E. Hancock of Wyeth-Lederle Vaccines, West Henrietta, and colleagues note that there is evidence that this glycoprotein may be the agent most strongly associated with the putative development of a Th2 phenotype following RSV infection early in life. They also point out that G protein "sensitizes mice for pulmonary eosinophilia" and that "Th2 cells are central to the pathogenesis of asthma."
To investigate, the researchers studied the anti-G protein responses in plasma and peripheral blood mononuclear cells (PBMCs) obtained from asthmatics and healthy controls. Their findings appeared in the December 15th issue of the Journal of Infectious Diseases.
The investigators found a "significant trend" connecting asthma severity and anti-G protein IgG1 and IgG2 titers. Furthermore, a similar relationship with anti-fusion (F) protein IgG3 titers "approached significance."
However, in further studies, recall responses of PBMCs from asthmatics and controls were similar and "were directed primarily against peptides representing the nonglycosylated region of G protein." Supernatant levels of IL-4, IL-5 and IL-13 were also similar, and the investigators conclude that the role of G protein in setting a Th2 response is not as clear in humans as it is in mice.
In a comment to Reuters Health, Dr. Hancock noted that these "early stage" data shed light on the contribution of RSV infection to asthma pathogenesis and "suggest the potential for specific attenuated vaccines to prevent RSV and possibly impact the proliferation of asthma."