Article Sections

Introduction

X-linked (Bruton) agammaglobulinemia (XLA) is a primary immunodeficiency disorder characterized by the absence of mature B cells.  Patients with XLA present with recurrent infections as transplacental immunoglobulin G (IgG) antibodies wane after age 6 months.

Pathogenesis

B cell maturation begins in the bone marrow, where hematopoietic stem cells differentiate into immature B cells ( Figure 1).  Immature B cells then migrate to secondary lymphoid tissues (eg, spleen, lymph nodes), where they complete maturation.  Mature B cells aggregate in the cortex of lymph nodes to form lymphoid follicles ( Figure 2).  Upon antigenic stimulation, mature B cells migrate to secondary follicles, where they proliferate and differentiate into immunoglobulin-producing plasma cells in the germinal center.

XLA is caused by a genetic mutation in the Bruton tyrosine kinase (

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Figures

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Tables

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