Abstract
Mannose-binding lectin (MBL) deficiency is relatively common occurring in ∼7% of the general population. Most individuals with MBL deficiency are clinically unaffected due to protective antibody adaptive immunity, and therefore never present for evaluation of recurrent infections. We sought to identify associated immunologic abnormalities in patients with MBL deficiency that may have influenced their clinical presentation and resulted in referral for evaluation. Retrospective chart review of all patients found to have MBL deficiency at Cardinal Glennon Children's Medical Center at Saint Louis University between 2000 and 2009. Twenty-two patients, 40% of 55 patients with MBL deficiency, were found to have concomitant selective antibody deficiency (SAD). At initial evaluation Streptococcus pneumoniae antibody titers were frequently nonprotective in both groups of patients. After S. pneumoniae vaccination, MBL-deficient patients with SAD developed protective antibody titers to 44% ± 13% of S. pneumoniae serotypes compared with 80% ± 15% in patients with isolated MBL deficiency (P = 0.0004). Patients with MBL deficiency and SAD had increased frequency of otitis media, pneumonia, and sepsis compared with patients with MBL deficiency alone. Prophylactic antibiotics were used more frequently in MBL deficiency with SAD compared with MBL deficiency, 90% versus 76%, as was intravenous immunoglobulin/subcutaneous gammaglobulin, 43% versus 6% (P = 0.002). CD27+ memory B cells were significantly decreased in MBL deficiency with concomitant SAD. SAD was identified in ∼40% of individuals with MBL deficiency. The large number of patients with MBL deficiency and concomitant SAD as well as the relative increase in recurrent otitis media, pneumonia, sepsis, and need for intravenous immunoglobulin seen in patients with both disorders strongly support evaluating for additional immunologic abnormalities in patients with MBL deficiency.
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