Differentiation of Common Variable Immunodeficiency From IgG Deficiency
Charles A. Filion, MDa,b, Sarah Taylor-Black, MDa,c, Paul J. Maglione, MD, PhDa, Lin Radigana, and
Charlotte Cunningham-Rundles, MD, PhDa New York, NY; Montreal, Quebec, Canada; and Concord, NH
An introduction and summary of a paper on a topic that affects many of the patients we care for.
What is already known about this topic? Common variable immunodeficiency (CVID) is defined by a deficiency in IgG
and one other isotype in addition to insufficient vaccine responses, whereas IgG deficiency does not meet all criteria for
CVID. Both immune defects confer susceptibility to sinopulmonary infections.
What does this article add to our knowledge? This large cohort study demonstrates that in contrast to IgG deficiency,
CVID is an immunodeficiency that presents with lower IgG levels, greater unresponsiveness to most vaccines, lower
percentages of memory and isotype switched-memory B cells, and higher prevalence of noninfectious complications.
How does this article impact current management guidelines? These data indicate that CVID and IgG deficiency do
not share the same disease spectrum, the former being associated with immunodysregulative manifestations and markers
of a more severe immune defect and may allow clinicians to better distinguish the 2 conditions.
BACKGROUND: Common variable immunodeficiency (CVID) and IgG deficiency are 2 of the more prevalent primary humoral immune defects. The former is defined by consensus with criteria for quantitative and qualitative antibody defects, whereas the latter is used to describe patients with reduced IgG, who commonly have recurrent sinopulmonary infections but do not fulfill CVID criteria. However, these patients are often given this diagnosis.
OBJECTIVE: To compare immunologic findings and clinical manifestations of 2 large cohorts of patients with CVID or IgG
deficiency to better delineate differences between these syndromes.
METHODS: We extracted clinical and laboratory data from electronic medical records of patients at our institution who had received International Classification of Disease codes for either
CVID, or IgG deficiency. We gathered immunoglobulin levels, lymphocyte subpopulation counts, and serological vaccine responses. In some patients, we performed flow cytometry to
determine percentages of memory and switched-memory B cells. We compiled and statistically compared clinical data related to infectious manifestations, bronchiectasis, autoimmune diseases, infiltrative inflammatory processes, and lymphoid malignancies.
RESULTS: In contrast to IgG-deficient patients, we found that patients with CVID had lower IgG levels, greater unresponsiveness to most vaccines, lower percentages of memory and
isotype switched-memory B cells, and lower CD4 T-cell counts. Clinically, patients with CVID presented similar rates of sinusitis and pneumonias, but a significantly higher prevalence of
bronchiectasis and especially noninfectious complications.
CONCLUSIONS: CVID and IgG deficiency do not share the same disease spectrum, the former being associated with immunodysregulative manifestations and markers of a more severe immune defect. These data may allow clinicians to distinguish these conditions and the management differences that these patients pose. 2018 American Academy of Allergy,
Asthma & Immunology (J Allergy Clin Immunol Pract