Th2 predominance and decreased NK cells in patients with hereditary angioedema.

BACKGROUND

In this study we included patients with hereditary angioedema (HAE) caused by decreased levels of C1 inhibitor (HAE-C1INH). An increased risk of autoimmune disorders, particularly systemic lupus erythematosus (SLE), has been reported in HAE-C1INH. This suggests that complement consumption affects adaptive immunity.

OBJECTIVE

To investigate lymphocyte subpopulations in relation to disease activity and complement activation in HAE-C1INH patients and matched controls.

METHODS

Flow cytometry of peripheral blood lymphocyte populations, measurements of complement and complement fragments, and collection of clinical data.

RESULTS

NK cell counts were lower in HAE-C1INH patients, and their frequencies were related to disease activity. The T helper (Th) cell balance was skewed towards more Th2 cells and less Th1 cells in HAE-C1INH patients compared to controls. There were also lower frequencies of class-switched B cells and plasmablasts in patients. Levels of C4 and the complement activation fragment C3d were related to disease activity.

CONCLUSIONS

Blood lymphocyte populations are altered in HAE-C1INH, a finding which may be of pathophysiological importance considering the increased risks of both autoimmunity and allergy associated with HAE-C1INH.