Different environmental influences on etiology of atopic diseases in European populations as a basis for study of geneenvironment interactions.

Atopy is a predisposition to hyperproduction of immunoglobulin E (IgE) against
common environmental allergens. Sensitization to various airborne and food allergens
contributes to different types of atopic diseases, including asthma, eczema, and allergic
rhinitis. The development of these diseases is influenced by both genetic and
environmental factors. Several loci and genes that control IgE level have been described
in different chromosomal regions. Some of them have been detected in several populations, others only in one or a few populations. These differences might be caused
by variations of genetic composition between populations, different lifestyles and/or by
environmental variations in major allergens triggering development of atopic diseases.
Thus, the environmental conditions may likely determine, which from the potential
atopy-controlling genes will operate in a certain population.
As the first step in study of such gene-environment interactions we analyzed the
specificity and intensity of sensitization to 40 different allergens in atopic patients from
the Czech Republic and Ukraine, representing two genetically not very distant
populations, which live in different environmental conditions. The atopic patients from
both countries displayed a higher reactivity to inhalant than to food allergens. We found
highly significant differences in sensitization to airborne allergens between patients from
the two countries. The most pronounced allergens for the atopic patients from Ukraine
were allergens from dust mites Dermatophagoides pteronyssinus (38.5%),
Dermatophagoides farinae (48.1%) and cat (44.2%). In the atopic patients from the
Czech Republic the level of sensitization to these allergens was similar, but the level of
sensitization to outdoor allergens, grasses and trees was dramatically higher. More than
68% of the patients from the Czech Republic in comparison with less than 25% of the
patients from Ukraine have been sensitized to cocksfoot, sweet vernal grass, timothy
grass and cultivated rye (Bonferroni-corrected P values ranged from 0.0007 to
0.000000003). More than 50% and 60% of the patients from the Czech Republic but only
2% and 19.2% of the patients from Ukraine reacted to alder (corrected P < 0.00009) and
birch (corrected P < 0.002), respectively. The higher sensitization to plant allergens of
the patients from the Czech Republic was present in those with asthma and rhinitis, but
not with dermatitis. The higher sensitization levels to outdoor allergens in the Czech
Republic suggest an influence of westernization on development of allergic reactivity.
Genetic analysis of atopic patients from these two countries will establish which geneloci
control development of atopy under different environmental conditions.