Chronic Spontaneous Urticaria: An Etiopathogenic Study

Importance: Exact etiopathogenesis of chronic spontaneous urticaria (CSU) remains elusive. Infections, pseudoallergens, autoimmunity, and contact sensitization are various postulated factors. Few studies are available measuring cytokine levels in CSU. Objectives: The aim was to study various etiological factors of CSU and levels of IL-6 and IFN-gamma in cases and controls, and correlation between various etiologies with the levels of the abovementioned interleukins in the cases. Design: Case-control study performed over 2 years with no follow-up of the participants. Setting: It was a referral-center-based study. Participants: Sixty patients of CSU and equal age and sex-matched healthy controls were recruited on the basis of convenience sampling. Exposures: Biochemical and hematological investigations with hepatitis serology, thyroid function tests, anti-thyroid antibodies, and levels IL-6 and IFN-gamma were performed in all cases and controls. All cases were subjected to ASST. Cases with all above negative tests were patch-tested with Indian standard series. Urticaria activity score (UAS7) was calculated for all the cases and repeated in patients with positive etiological factor after 3 weeks (improvement after allergen or drug avoidance, treatment of infection). Outcomes: To study the various etiological factors (food, infection, autoimmunity, autoreactivity, and contact sensitization) and the levels of IL-6 and IFN-gamma in patients of chronic spontaneous urticaria. Results: Etiology was ascertained in 75% of patients (autoimmunity: 50%, contact sensitization: 21.67%, food and drug allergy: 1.67% each). Mean values of the interleukins and anti-thyroid antibodies were significantly higher in cases versus controls. Levels of IFN-gamma were significantly elevated in patients with higher UAS7 scores. Conclusion: Antithyroid antibodies, ASST, and patch testing are important tools and should be considered in patients of CSU after a thorough history and history-based workup. Elevated levels of IL-6 and IFN-gamma in cases suggest that both Th1 and Th2 type of immune responses are implicated in pathogenesis of CSU.