Keywords:
Abstract:
In the past few decades, a dramatic increase in the prevalence of allergic disease in Western developed countries has led to a large disproportion in the prevalence of asthma and allergy between Western and Eastern countries.1,2 Australia and China have one of the highest and lowest rates of asthma and allergies, respectively, as demonstrated in the International Study of Asthma and Allergies in Childhood.3,4 Immigrants who migrate from low-risk countries to high-risk countries experience a gradual increase in allergic diseases to the same level as the local population.5,6 We hypothesized that there is a shift in the immune response related to asthma and allergy after immigrants adapt to the Western environment, which might explain the West-East gradient in the incidence of asthma and allergic conditions between developed and developing countries.
We recruited age- and sex-matched Chinese immigrants living in Western Australia for less than 6 months (newly arrived, n = 22) or more than 5 years (long-term, n = 22) (see Table E1in this article's Online Repository at www.jacionline.org). Skin prick, total, and specific IgEtest values to common allergens were measured (see Table E2 in this article's Online Repository at www.jacionline.org). Long-term immigrants had higher allergic symptoms (itchy rash, eczema, hay fever) and sensitization to grass allergens, as well as higher body mass index and blood pressure. Whole blood from each participant was added to Toll-like receptor (TLR) stimulation plates containing the following 6 TLR ligands: PAM3CSK4 (PAM; TLR-2/1), polyinosinic-polycytidylic acid (p:IC; TLR-3), LPS (TLR-4), resiquimod (R848; TLR-7/8), peptidoglycan (PGN; nucleotide-binding oligomerization domain-containing protein 1/2), and muramyl dipeptide (MDP; nucleotide-binding oligomerization domain-containing protein 2). The following cytokine levels were measured in the supernatant: ENA-78, GM-CSF, GRO-alpha, IFN-α, IFN-β, IFN-γ, IL-10, IL-12p40, IL-12p70, IL-18, IL-1α, IL-1β, IL-1RA, IL-23, IL-6, IL-8, IP-10, MCP-1, MCP-3, M-CSF, MIG, MIP-1β, and TNF-α.