Reference : Selective defect of anti-pneumococcal IgG in a patient with persistent polyclonal B c...
Scientific journals : Article
Human health sciences : Hematology
Selective defect of anti-pneumococcal IgG in a patient with persistent polyclonal B cell lymphocytosis.
Hafraoui, Kaoutar mailto [Centre Hospitalier Universitaire de Liège - CHU > > Hématologie clinique >]
Moutschen, Michel mailto [Université de Liège - ULiège > Département des sciences cliniques > GIGA-R:Immunopath. - Maladies infect. et médec. inter. gén. >]
Smet, Julie [> > > >]
Mascart, Francoise [> > > >]
Schaaf-Lafontaine, Nicole mailto [Centre Hospitalier Universitaire de Liège - CHU > > Hématologie biologique et immuno hématologie >]
Fillet, Georges mailto [Centre Hospitalier Universitaire de Liège - CHU > > Hématologie clinique >]
European Journal of Internal Medicine
Elsevier Science
Yes (verified by ORBi)
[en] Antibodies, Bacterial/immunology ; Antibody Specificity ; B-Lymphocytes/immunology ; Epitopes ; Female ; Humans ; Immunoglobulin Class Switching/immunology ; Immunoglobulin D/immunology ; Immunoglobulin G/immunology ; Immunoglobulin M/immunology ; Immunophenotyping ; Lymphocytosis/immunology/therapy ; Middle Aged ; Pneumococcal Infections/immunology/therapy ; Pneumococcal Vaccines/administration & dosage/immunology ; Streptococcus pneumoniae/immunology
[en] BACKGROUND: Persistent polyclonal B cell lymphocytosis (PPBL) is a rare condition characterized by increased IgM and large excess of B cells with an IgD(+) CD27(+) phenotype. In normal individuals, these cells play a central role in the defense against pneumococcal infection. So far, few studies have characterized humoral immune responses in PPBL patients. We therefore measured IgG directed against S. pneumoniae antigens in a 51 yr-old woman with PPBL before and after vaccination with a pneumococcal 23-valent polysaccharide vaccine. METHODS: Antibodies against pneumococcal antigens were measured first with an overall immunoassay using microplates coated with the 23-valent pneumococcal vaccine. A serotype-specific test was also performed according to the WHO consensus protocol. RESULTS: Despite a large number of IgD(+) CD27(+) cells, our patient had low baseline titers of IgG directed against pneumococcal antigens and did not significantly respond to a 23-valent polysaccharide vaccine against S. pneumoniae. On the contrary, she had good titers of IgG directed against tetanus toxoid. CONCLUSION: IgM(+) IgD(+) CD27(+) cells which accumulate in this patient with typical PPBL patient failed to perform IgG isotype switch after a polysaccharide vaccine. The potential mechanisms and relationships with the main features of PPBL are discussed. Further studies on a larger number of similar patients are needed.

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