Immune Deficiencies Caused by B Cell Defects

Primary antibody deficiencies (PADs) are the most common inherited immunodeficiencies in humans. The use of novel approaches, such as whole-exome sequencing and mouse genetic engineering, has helped identify new genes involved in the pathogenesis of PADs and has enabled the characterization of the molecular pathways that are involved in B cell development and function. We will summarize the different PADs in terms of their known or putative mechanisms that underlie B cell development in bone marrow, migration to secondary lymphoid organs, survival, and activation, although these different mechanisms can share the same molecular pathways. The defect leading to PAD can be B cell-specific or affecting also other(s) hematopoietic or nonhematopoietic lineage(s). Finally, most of PADs remain not molecularly defined so far.