ObjectiveSystemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by flare-ups, the causes of which are not known. In accordance with new concepts in stress research, this study investigated whether daily psychosocial stressors interfere with immunological processes in SLE. Because such processes are unique to each individual, single-case design using time-series analysis (Box and Jenkins) was applied.MethodsA 40-year-old woman with SLE (last flare-up September 1995) was interviewed initially to determine major life events and difficulties (using the Life Events and Difficulties Schedule) in the previous 2 years. She was then observed for 63 days. Urine neopterin, an immunological parameter demonstrated to parallel disease activity in SLE patients, was measured in daily overnight urine. Daily incidents were identified weekly by the Incidents and Hassles Inventory and independently rated. Intervening factors, including infections, medication, and lifestyle, were controlled.ResultsRetrospectively, data obtained from the Life Events and Difficulties Schedule indicated that major life events and difficulties had preceded the patient’s last flare-up in 1995. Although there were no clinical signs of SLE during this prospective study of 63 days, cross-correlational analyses revealed that “moderately” stressful incidents associated with higher levels of emotional irritation (lag 0: +0.271,p< .05) predicted an increase in urine neopterin the following day (lag 1: +0.441,p< .05). Moreover, a 7-day cyclicity in neopterin levels that corresponded to the weekly examinations and interviews was found.ConclusionsThis study showed a causal relationship between psychosocial stressors and urine neopterin concentrations that may be related to SLE disease activity. Furthermore, the workability of an integrative approach using single-case design and time-series analysis in psychoneuroimmunology was demonstrated for the first time.