Could TH1 and TH2 diseases coexist?: Evaluation of asthma incidence in children with coeliac disease, type 1 diabetes, or rheumatoid arthritis:: A register study

Background: Asthma is generally regarded as a disease with strong T(H)2-type cytokine expression, whereas in autoimmune disorders, such as coeliac disease (CD), insulin-dependent diabetes mellitus (IDDM), and rheumatoid arthritis (RA), T(H)1-type expression is seen. According to the cross-regulatory properties of T(H)1 and T(H)2 cells, one would assume that these diseases exist in different patient populations. Objective: We sought to test the hypothesis that asthma could exist in children with T(H)1-type diseases, such as CD, IDDM, and RA. Methods: Comparison was made of the cumulative incidence of asthma in children with CD, IDDM, or RA by linking Finnish Medical Birth Register data on the whole 1987 birth cohort (n = 60,254 births) with the data of several national health registers to obtain information on the incidences of these diseases during the first 7 years of life. Results: The cumulative incidence of asthma in children with CD (24.6%) or RA (10.0%) was significantly higher than in children without CD (3.4%) or RA (3.4%; P < .001 and P = .016, respectively). Asthma tended to be more common in children with IDDM than in children without IDDM. Conclusion: These data indicate that the T(H)1 and T(H)2 diseases can coexist, indicating a common environmental denominator behind the disease processes.