Primary Deficiencies of Humoral Immunity

• Maternally acquired IgG & IgA protects infants for the first 6 months
• In X linked hyper - IgM syndrome the defect in CD40L prevents antibody class switching
• In X linked hyper - IgM syndrome, communication between T cells and APCs is disrupted
• Selective IgA deficiency is the most common primary immunodeficiency disorder
• Bruton tyrosine kinase deficiency is the only one of the humoral immune deficiencies in which there are no peripheral immature and mature B cells (no CD19+ cells)
• Transient hypogammaglobulinemia of infancy has decreased IgG & increased risk of upper respiratory system infections
• Bruton’s X-linked agammaglobulinemia (XLA) is X - linked recessive, has normal T cells & very low serum levels of all isotypes
• X-linked hyper-IgM syndrome / CD40L deficiency

  • Its absence in B cells results in:
  • Poor organisation of GCs
  • No antibody class switch
  • Lack of memory B cells
  • Reduced somatic hypermutation
• Selective A has normal IgG & IgM, recurrent bacterial & viral infections