Common Variable Immunodeficiency (CVID)
CVID is a heterogeneous group of disorders involving both B-cell and T-cell dysfunction. The predominant manifestation is IgG, IgM, and IgA hypogammaglobulinemia often resulting in the very low levels seen in Agammaglobulinemia (XLA).
Features distinguishing CVID from XLA include equal sex distribution, onset of symptoms later in life, and the presence of circulating B cells. Although the underlying immunologic defect is heterogeneous (ICOS, CD19, TACI, or BAFF-R deficiency), most patients exhibit a primary B-cell defect that results in a failure to mature into Ig-secreting plasma cells. Like selective IgA deficiency, CVID is probably a genetic disorder in most cases, although some cases may be truly acquired and secondary to a viral infection or an adverse drug effect (i.e., cytotoxic therapy). Notably, patients with selective IgA deficiency are at increased risk of CVID evolution, which suggests that a common pathogenetic defect exists.
Rheumatologic Manifestations of Common Variable Immunodeficiency
Extracellular, and encapsulated bacteria (S. pneumoniae, H. influenzae, S. aureus)
Mycoplasma, particularly Ureaplasma urealyticum
Aseptic, possibly autoimmune, arthritis
Sarcoid-like lesions in lung, liver, lymph node, skin; occur in 5-10% of patients
Organ-specific autoimmune disorders (pernicious anemia, autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, others); occur in 20% of patients