Drug allergy and autoimmune diseases.

Systemic autoimmune diseases are reportedly associated with a high frequency of drug allergies. In particular, systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), and adult-onset Still's disease (AOSD) have recently drawn attention. Based on previous reports, drug allergies have been reported in 17.1-63%, 7-40.1%, and 17.6-54% of patients with SS, SLE, and AOSD patients, respectively. Antimicrobial agents, including sulfa drugs and nonsteroidal anti-inflammatory drugs, are the most common causative agents of drug allergies. However, few studies have examined in detail the relationship between drug eruptions, a major symptom of drug allergy, and systemic autoimmune diseases, and their actual status remains unclear. These autoimmune diseases commonly exhibit a diverse range of skin manifestations in the course of these diseases, rendering it may be difficult to determine whether it is a true drug eruption. Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), a fatal, severe drug eruption, has also been associated with autoimmune diseases. The development of SS-like symptoms after SJS/TEN onset and high prevalence of anti-SS-A antibodies in SJS/TEN are intriguing observations. Although the presence of SLE is known to be a risk factor for SJS/TEN, common pathological conditions, such as excessive immune status, abnormal function of regulatory T cells, and neutrophil extracellular traps in autoimmune diseases such as SS and SLE, are potentially involved in the development of drug eruptions.