Selective defect of anti-pneumococcal IgG in a patient with persistent polyclonal B cell lymphocytosis.

Abstract

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.

• Authors: Kaoutar Hafraoui, Michel Moutschen, Julie Smet, Françoise Mascart, Nicole Schaaf-Lafontaine, Georges Fillet
• Journal: European journal of internal medicine (Eur J Intern Med) Vol. 20 Issue 3 Pg. e62-5 (May 2009) ISSN: 1879-0828 [Electronic] Netherlands
• PMID: 19393481 (Publication Type: Case Reports, Journal Article)

Chemical References

• Antibodies, Bacterial
• Epitopes
• Immunoglobulin D
• Immunoglobulin G
• Immunoglobulin M
• Pneumococcal Vaccines

Topics

• 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)