Preserved antibody levels and loss of memory B cells against pneumococcus and tetanus after splenectomy: tailoring better vaccination strategies.

Splenectomized patients are exposed to an increased risk of septicemia caused by encapsulated bacteria. Defense against infection is ensured by preformed serum antibodies produced by long-lived plasma cells and by memory B cells that secrete immunoglobulin in response to specific antigenic stimuli. Studying a group of asplenic individuals (57 adults and 21 children) without additional immunologic defects, we found that spleen removal does not alter serum anti-pneumococcal polysaccharide (PnPS) IgG concentration, but reduces the number of PnPS-specific memory B cells, of both IgM and IgG isotypes. The number of specific memory B cells was low in splenectomized adults and children that had received the PnPS vaccine either before or after splenectomy. Seven children were given the 13-valent pneumococcal conjugated vaccine after splenectomy. In this group, the number of PnPS-specific IgG memory B cells was similar to that of eusplenic children, suggesting that pneumococcal conjugated vaccine administered after splenectomy is able to restore the pool of anti-PnPS IgG memory B cells. Our data further elucidate the crucial role of the spleen in the immunological response to infections caused by encapsulated bacteria and suggest that glycoconjugated vaccines may be the most suitable choice to generate IgG-mediated protection in these patients.

Iron-related MRI images in patients with pantothenate kinase-associated neurodegeneration (PKAN) treated with deferiprone: results of a phase II pilot trial.

BACKGROUND: The safety and efficacy of the oral iron-chelating agent deferiprone on magnetic resonance pallida iron concentration and on clinical status were investigated in 10 patients affected by pantothenate kinase-associated neurodegeneration. METHODS: Nine patients (age range, 7-39 years) completed the study. RESULTS: A significant median reduction in globus pallidus iron content as assessed by T2* relaxometry (and calculated R2* maps; P=.008) was observed at the end of the study. None of the patients demonstrated a change in clinical status as assessed by the Burke-Fahn and Marsden Dystonia Rating scales and by a health-related quality-of-life scale. Deferiprone was well tolerated, and no serious adverse events occurred. CONCLUSIONS: Future trials assessing the clinical efficacy of chelating therapy should consider early symptomatic patients and a longer treatment period.