Predominantly antibody deficiencies

Predominantly antibody deficiencies is a heterogeneous group of disorders, ranging from a severe reduction of all serum immunoglobulin isotypes with an absence of B cells to specific antibody deficiency with normal serum immunoglobulins. Predominantly antibody deficiencies are the most common forms of PIDs, which constitute of more than half of all PIDs. Dysgammaglobulinemia is the main characteristic of the patients, which renders the patients susceptible to infections with encapsulated bacteria. The most common infectious complication in patients with antibody deficiencies is sinopulmonary infections. Patients with antibody deficiencies also experience autoimmunity, enteropathy, lymphoproliferation, and malignancies. Due to the heterogeneous manifestation of antibody deficiencies and the impact of early diagnosis and Ig replacement therapy on long-term complications and quality of life of patients, a timely and comprehensive approach should be considered in the suspected cases. We discussed in this chapter the four main categories of predominantly antibody deficiencies based on the defects in B cell developmental stages including early B cell defects, terminal B cell defects, class switching defects and isolated isotype, light chain, or functional B cell deficiencies with generally normal numbers of B cells.