Evaluation of B Lymphocyte Deficiencies
John D. Vickery, Christie F. Michael and D. Betty Lew
Affiliation: The Children's Foundation Research Center; and Department of Pediatrics, College of Medicine, University of Tennessee, Memphis, Tennessee, USA.
The most common of the primary immunodeficiency diseases are those that involve inadequate antibody
production. The characteristic presentation of these disorders is recurrent sinopulmonary infections. An arrest in B cell
development at the pre-B cell stage leads to agammaglobulinemia and an insignificant number of B cells. X-linked
agammaglobulinemia is the most common of these developmental arrests while the autosomal recessive
agammaglobulinemias comprise a small minority of the total cases. Likewise, the most common form of the hyper-IgM
syndromes (CD40 ligand deficiency) is X-linked. Of the autosomal recessive forms, CD40 deficiency is basically
identical to the X-linked form in its clinical phenotype where, in addition to inadequate antibody production, there is
defective T cell signaling through the CD40-CD40L interaction. Aside from CD40 deficiency, the other recessive forms
of hyper-IgM syndrome have adequate T cell function. IgA deficiency is the most common and the most benign of the B
cell disorders. Common variable immunodeficiency is diverse in its presentation and clinical course. The pathophysiology
of this disease is multifactorial and frequently ill defined, often making it a diagnosis of exclusion. A working knowledge
of identifiable PIDDs is essential in both recognizing when to suspect immunodeficiency and making a diagnosis.
Keywords: B lymphocyte, antibody, deficiencies, clinical evaluation.
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