Humoral alteration in 22q11.2 deletion syndrome patients

Objective: To investigate humoral compartment at diagnosis and during follow-up in patients with 22q11.2 Deletion Syndrome (22q11DS). Methods: A retrospective and prospective multicenter study was conducted with 165 patients in the context of the Italian Network for Primary Immunodeficiencies. Patients were investigated for serum immunoglobulin, testing specific antibody titers to recall antigens and proliferative responses to phytohemagglutinin (PHA) and OKT3. Lymphocyte subsets were assessed by flow cytometric analysis. Results: The cohort consisted of 96 males and 69 females; median age at diagnosis was 4 months (range 0 to 35 years). Eighty out of 165 patients had a history of recurrent and/or severe infections and 41% patients received at least one prophylactic treatment. During follow-up the frequency of autoimmune manifestations increased, severe infections and antibiotic prophylaxis decreased. We reported hypogammaglobulinemia in 34% of patients at diagnosis, confirmed during follow-up. Total lymphocytes and T-cells subsets were decreased in most of 22q11DS patients, although these immunological abnormalities did not correlate to risk of infections. Lymphocyte proliferation in response to mitogens and antigens was normal/ in the lower levels of normality, in most of patients. Our preliminary data showed a decrease of B cell memory. Conclusions: Not only T-cell but also B- cell compartment should be routinely investigated in 22q11DS patients with an history of recurrent infections and autoimmune manifestations. These data could help to better define, in these patients, follow-up and clinical management with a specific antimicrobial treatment and/or intravenous immunoglobulin therapy.