Lymphocyte subsets and activation markers in patients with acute episodes of idiopathic anaphylaxis

Background: Idiopathic anaphylaxis (IA), a type of anaphylaxis in which no external allergen can be identified, is a corticosteroid-responsive disease, that suggests that it may have an immunologic pathogenesis. Objective: The objective of this study is to compare patients with acute episodes of IA with normals, patients with chronic idiopathic urticaria, and patients with IA in remission relative to lymphocyte subsets and activation markers. Methods: This is a prospective cohort study of 38 adults: 5 normals, 4 idiopathic urticaria, 11 IA patients in remission, 9 IA patients with acute attacks who had not yet received prednisone, and 9 IA patients who had received prednisone. The main outcome measures were lymphocyte subset and activation markers determined by two and three color flow cytometry (CD2, CD3, CD4, CD5, CD8, CD16, CD19, CD23, CD25, CD56, and HLA-DR). Results: Comparing patients with acute IA with those in remission, the only significant difference was that the acute IA patients had a significantly higher percentage of CD3⁺HLA-DR⁺ cells. Normals had a significantly lower percentage of CD3⁺HLA-DR⁺ cells than all other groups. Patients with acute IA on prednisone as well as IA patients in remission had a significantly higher percentage of CD 19⁺ CD23⁺ cells than normals. Conclusions: These results suggest that there are more activated T cells in patients with acute episodes of IA than in patients in remission. Perhaps, these activated T cells have a role in the pathogenesis of IA.