Abstract
ObjectiveHere we report a case of a splenectomized white woman with natalizumab-associated progressive multifocal leukoencephalopathy (PML), occurring as early as after 11 infusions and provide blood fluorescence-activated cell sorting (FACS) analyses before and after natalizumab treatment.DesignThis is a report of a single case with immunological studies.MethodsMethods comprised neurologic examination, magnetic resonance imaging, and cerebrospinal fluid (CSF) studies as well as immune cell FACS analyses from blood.ResultsDiagnosis of PML was established after positive John Cunningham virus (JCV) DNA was detected in the CSF. An immune reconstitution inflammatory syndrome was treated with repeated cycles of steroid pulses and intravenous immunoglobulins. Reduced numbers of memory B cells, which might play an important role in antiviral immune response, were detected in the blood. Moreover the percentage of CD19+ B cells was elevated in our post-splenectomy patient as compared to a control cohort of multiple sclerosis (MS) patients under natalizumab therapy.ConclusionSplenectomy may increase the risk for the development of natalizumab-associated PML via effects on the B cell compartment. It may be regarded as a risk factor in MS patients independent from the duration of disease.
Highlights
Before the era of natalizumab as first monoclonal antibody in multiple sclerosis (MS) therapy arose, progressive multifocal leukoencephalopathy (PML), which is caused by the John Cunningham polyoma virus (JCV), was more or less exclusively seen in immunocompromised individuals, especially those suffering from human immunodeficiency virus (HIV) infection [1,2]
Splenectomy may increase the risk for the development of natalizumab associated PML affecting the B cell compartment and should regarded as a risk factor in MS patients independent from the duration of disease
If therapy with natalizumab is considered in a splenectomized MS patient, benefits of the therapy should be well balanced with the possibly increased risk for the development of PML
Summary
Before the era of natalizumab as first monoclonal antibody in multiple sclerosis (MS) therapy arose, progressive multifocal leukoencephalopathy (PML), which is caused by the John Cunningham polyoma virus (JCV), was more or less exclusively seen in immunocompromised individuals, especially those suffering from human immunodeficiency virus (HIV) infection [1,2]. Absolute lymphocyte counts are persistently elevated due to an increase in the absolute CD4, CD8, B cell, and natural killer (NK) cell numbers [6]. Similar changes can be observed in natalizumabtreated patients [7,8]. Natalizumab treatment may elicit prominent effects on the composition of the circulating B cell populations. In particular circulating B cells and especially pre-B cells are most prominently elevated among the immune cell subsets [9,10,11]. Likewise dominant changes on the peripheral blood B cell compartment have been observed in splenectomized patients.
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