Chronic norovirus infection in primary immune deficiency disorders: an international case series.

OBJECTIVE: Predictive factors associated with clinical outcomes of chronic norovirus infection (CNI) in primary immunodeficiency diseases (PIDD) are lacking. METHOD: We sought to characterize CNI using a multi-institutional cohort of patients with PIDD and CNI using the Clinical Immunology Society's CIS-PIDD Listserv e-mail group. RESULTS: Thirty-four subjects (21 males and 13 females) were reported from centers across North America, Europe, and Asia. All subjects were receiving high doses (median IgG dose: 1200 mg/kg/month) of supplemental immunoglobulin therapy. Fifty-three percent had a complete absence of B cells (median B-cell count 0; range 0-139 cells/µL). Common Variable Immune Deficiency (CVID) subjects manifested a unique phenotype with B-cell lymphopenia, non O+ blood type, and villous atrophy (logistic regression model, P = 0.01). Five subjects died, all of whom had no evidence of villous atrophy. CONCLUSION: While Norovirus (NoV) is thought to replicate in B cells, in this PIDD cohort of CNI, B-cell lymphopenia was common, indicating that the presence of B lymphocytes is not essential for CNI.

Effective management of severe cutaneous mastocytosis in young children with omalizumab (Xolair® ).

Omalizumab (Xolair® ) is an anti-IgE monoclonal antibody, which may benefit adults with systemic mastocytosis. We report effective treatment with omalizumab in two toddlers with severe diffuse cutaneous mastocytosis. Our cases offer preliminary evidence to support the safe use of omalizumab in paediatric patients with cutaneous mastocytosis.