- Immunoglobulin E (IgE) is a molecule involved in allergic diseases.
- Serum IgE levels are influenced by genetics, allergen exposure, and some environmental factors.
- A new study investigates if alcohol may be one such environmental factor.
- Low to moderate alcohol consumption was found to be associated with increased IgE levels.
Immunoglobulin E (IgE) is a molecule involved in allergic diseases. Atopy - the genetic predisposition to develop IgE antibodies against some antigens in the environment - affects as much as 30 percent of the population, and is believed to be increasing in frequency. In addition to the influence of genetics and allergen exposure, serum IgE levels can also be increased by a number of factors that include parasitic and other infections, neoplasms (abnormal tissue growth) and exposure to certain environmental factors. A study in the January issue of Alcoholism: Clinical & Experimental Research investigates if alcohol may be one such environmental factor.
"In prior studies we observed that alcoholics have increased IgE values," said Arturo González-Quintela, associate professor of internal medicine at the Complejo Hospitalario Universitario de Santiago, Spain and corresponding author of the study. "In the present study, we focused on the possible influence of minor quantities of alcohol intake, that is, 'normal consumption' or what is considered below the range of alcohol abuse. To our knowledge, this is the first study to focus on the association of low to moderate alcohol intake and both total and specific serum IgE levels."
A total of 460 patients (251 males, 209 females) were recruited from an adult allergy clinic in Spain. Based on skin-prick tests to common aeroallergens, 325 (71%) were classified as atopic and 135 (29%) as non-atopic. Most of the atopic patients (253 or 78%) were allergic to house dust mites. Using 10 grams as a measure of one drink, 260 patients (57%) were found to consume a median of 30 grams of alcohol per week, and 200 patients (43%) were considered abstainers. Total serum IgE was measured in all patients, and serum specific IgE (for specific allergies) were measured in atopic patients.
"Our research found that regular alcohol intake higher than 70 grams per week (or more than one drink per day) was associated with increased total serum IgE levels in the patients studied," said González-Quintela. "In patients allergic to house dust mites, regular alcohol intake was associated with increased serum levels of specific IgE against these mites."
"These findings do not merely support the suggestion that alcohol simply is a risk factor for developing allergies," observed Thomas R. Jerrells, professor of pathology and microbiology at the University of Nebraska Medical Center and the Omaha VA Medical Center. "The study results indicate that consumption of alcohol may result in abnormal immune responses or that the control of the immune system is affected. This leads to questions about the significance of the increased response to allergens by drinkers. If alcohol somehow affects the control of the immune response to these allergens, an exaggerated response would be expected."
Jerrells speculated that alcohol, either directly or indirectly through metabolites, might non-specifically activate a very complicated function of the immune system to produce IgE. An alternative possibility is that alcohol, again directly or indirectly, might activate cells that carry pre-formed IgE to release the IgE. Jerrells added that cells in various tissues, especially the gut, have surface IgE such as mast cells.
Nonetheless, despite results suggesting that even low to moderate alcohol consumption may affect the immune system, study authors show caution in extending these findings beyond the specific results.
"It is important to realize that it cannot be concluded," said González-Quintela, "that alcohol intake increases the likelihood of either developing allergic sensitization to aeroallergens such as dust mites, or developing more severe symptoms in patients already sensitized. Nor can it be concluded that alcohol intake should be avoided by allergic patients."
González-Quintela said that ongoing, unpublished studies indicate that, rather, alcohol intake is likely associated with a variable rate of sensitization to distinct aeroallergens. In other words, the sensitization rate either increases or decreases depending on the allergen considered. Furthermore, allergic sensitization depends on multiple variables - including socioeconomic conditions - that cannot be always controlled for in observational or non-experimental studies.
"Not all atopic subjects develop allergic symptoms," he said. "In addition to a genetic background, they will also need allergen exposure. Moreover, some environmental factors more than others favor allergic or IgE-mediated immune responses. We simply need more research to improve the understanding of allergic diseases and what role alcohol consumption may play."
Co-authors of the Alcoholism: Clinical & Experimental Research paper included: C. Vidal of the Department of Allergy, M.J. Domínguez-Santalla of the Department of Internal Medicine, S. Lojo of the Department of Biochemistry, and F. Gude of the Department of Clinical Epidemiology - all at the Complejo Hospitalario Universitario de Santiago, Spain. The study was funded by the Fondo de Investigaciones Sanitarias of the Spanish Ministry of Health.