Asthma and
autoimmune diseases apparently have little to share except for the involvement of the immune system in both types of disorder. However, epidemiological studies have shown that
asthma and
Type 1 diabetes, a typical
autoimmune disease, are associated at the population level, and some experimental findings have suggested that autoimmune mechanisms might be operating in
asthma as well. Female preponderance, increased incidence of
antinuclear autoantibodies and detection of
autoantibodies against either bronchial epithelial
antigens or endothelial
antigens in patients with nonallergic
asthma suggest that the disease may have an autoimmune basis. Approximately 50% of patients with nonallergic
asthma react to
intradermal injection of autologous serum, indicating the presence of circulating vasoactive factors and suggesting an autoreactive mechanism. Recent findings in experimental animals support the involvement of an autoreactive mechanism in allergic
asthma as well, indicating that human alpha-
nascent polypeptide-associated complex, identified as an
IgE-reactive
autoantigen, has the potential to sensitize and induce immediate skin reactions and airway
inflammation. In summary,
asthma is a heterogeneous disorder characterized by chronic
inflammation of the respiratory airways that can be triggered by
allergen exposure or by other mechanisms, possibly autoreactive/autoimmune. The autoimmune hypothesis is further, indirectly, supported by the response to immunosuppressive drugs.