"Common variable immunodeficiency: Challenges for diagnosis"

Diverse phenotypic manifestations of small intestinal mucosa in non-infectious common variable immunodeficiency bowel disease: A case report

BACKGROUND

Common variable immunodeficiency (CVID) is a primary antibody immunodeficiency disorder characterized by diminished IgG levels. Despite ongoing research, the precise pathogenesis of CVID remains unclear. Genetic factors account for only 10%-20% of cases, with an estimated incidence of 1 in 10000 to 1 in 100000, affecting individuals across all age groups.

CASE SUMMARY

We report the case of a 32-year-old man with CVID who presented with a chief complaint of "recurrent diarrhea and significant weight loss over the past 2 years". Laboratory tests on admission showed fat droplets in stool, while other parameters were within normal ranges. Gastroscopy revealed a smooth gastric mucosa without bile retention or signs of Helicobacter pylori infection; however, the mucosa of the descending segment of the duodenum appeared rough. Further evaluation of the small intestine using computed tomography indicated no abnormalities. Finally, the whole-small bowel double-balloon enteroscopy (DBE) was performed, which revealed various phenotypic changes in the small intestinal mucosa. The patient was diagnosed with CVID, which improved after immunoglobulin therapy, with favorable follow-up outcomes.

CONCLUSION

Non-infectious enteropathy in CVID is rare. Therefore, DBE is essential for diagnosing small intestinal involvement in such cases.

Longitudinal monitoring of class-switched memory-B cell proportions identifies plausible germinal center failure in patients with suspected immune disorders

A reduced proportion of peripheral class-switched memory B cells (CSM-B cells) is presumed to indicate ineffective germinal activity. The extent that this finding corresponds to a plausible germinal center failure pathophysiology in patients not diagnosed with CVID or hyper IgM syndrome is not known. We asked if patients with low CSM-B cells are more likely to demonstrate failure to produce serum IgA and IgG than counterparts with nonreduced class-switched memory B cell levels, regardless of diagnosis. Patients with low CSM-B cell levels regardless of diagnosis were retrospectively compared with their counterparts without CSM-B cell reductions for demographics and serum immunoglobulin levels. Patients were further divided based on whether CSM-B cell levels remained low over time or fluctuated, and these groups were compared for serum immunoglobulin levels and diagnoses. Of 305 patients, those with CSM-B cell (n = 50) reductions were more likely to have low serum IgA and IgG than those without reductions. Of the 78 patients in whom CSM-B cells were measured repeatedly over time, 21 patients had low CSM-B cell levels, but this finding was persistent in only 10. Patients with persistent CSM-B cell reductions universally had severe serum IgA and IgG deficiencies and patients with transient CSM-B cell reduction often did not. These two groups contained divergent diagnoses and likely represent separate pathophysiologic groups. Quantifying CSM-B cells as a percentage of CD27+ B cells repeatedly over time is a robust approach to identifying patients with a plausible germinal center failure endotype.

The role of immunophenotyping in common variable immunodeficiency: a narrative review

Common variable immunodeficiency (CVID) is a heterogeneous primary immunodeficiency (PID) characterized by an impaired immunoglobulin production, in association with an increased susceptibility to infections and a diversity of clinical manifestations. This narrative review summarizes immunophenotypic abnormalities in CVID patients and their relevance for diagnosis and disease classification. A comprehensive search across four databases - PubMED, Web of Science, EMBASE and Google Scholar - yielded 170 relevant studies published between 1988 and April 31, 2023. Over the past decades, the role of immunophenotyping in CVID diagnosis has become evident by identifying "hallmark" immunophenotypic aberrancies in patient subsets, with some now integrated in the consensus diagnostic criteria. Furthermore, the role of immunophenotyping in subclassifying CVID in relation to clinical presentation and prognosis has been extensively studied. Certain immunophenotypic patterns consistently correlate with clinical manifestations and/or subsets of CVID, particularly those associated with noninfectious complications (i.e. low switched memory B cells, shifts in follicular helper T cell subsets, low naïve CD4+ T cells, low regulatory T cells, and expansion of CD21low B cells, often associated with autoimmunity and/or splenomegaly). Also, efforts to associate subset levels of innate immune cells, such as Natural Killer (NK) cells, invariant (i)NKT cells, innate lymphoid cells (ILCs), and dendritic cells (DCs) to CVID complications are evident albeit in a lesser degree. However, inconsistencies regarding the role of flow cytometry in classification and prognosis persist, reflecting the disease complexity, but probably also cohort variations and methodological differences between published studies. This underscores the need for collaborative efforts to integrate emerging concepts, such as standardized flow cytometry and computational tools, for a more precise CVID classification approach. Additionally, recent studies suggest a potential value of (epi)genetic-based molecular assays to this effort.

Equine common variable immunodeficiency: lessons from 100 clinical cases

The clinical manifestation of recurrent fevers and infections alerts the clinician to the possibility of an underlying immunodeficiency. Common variable immunodeficiency (CVID) in the horse is a rare late-onset, non-familial immunologic disorder of B cell depletion and/or dysfunction with resultant inadequate antibody production. The most common clinical presentations in horses with CVID are recurrent upper and/or lower respiratory infections, meningitis and/or ataxia, cholangiohepatitis, infectious colitis, infectious dermatitis, and severe gastrointestinal parasitism. Immune-mediated and lymphoproliferative conditions are additional clinical features. The diagnosis of CVID in horses is based on persistent hypogammaglobulinemia primarily caused by a serum IgG concentration below 10.00 g/L in at least 2 different measurements, often accompanied by a serum IgM concentration below 0.50 g/L. Most horses with CVID show a persistent peripheral blood B cell distribution below 6% of total circulating lymphocytes, indicating severe B cell paucity or depletion, but the B cell distribution can be within the normal reference interval. Post-mortem findings add diagnostic information about the distribution of B and T cells in lymphoid tissues. Clinical management of horses with immunodeficiency is intense and expensive, and these factors weigh on the difficult decision of elective euthanasia. To date, no genetic mutation has been identified in horse patients with CVID, and the large number of breeds of single-affected individuals in a same herd or immediate lineage from various parts of the U.S. and the world do not point at an obvious inheritable mechanism of disease or environmental risk factors. This article describes the clinical and immunological findings in 100 cases, and comparisons with the disease in human patients.

Small Bowel Villous Atrophy in a Young Patient: A Challenging Diagnosis

Common variable immunodeficiency enteropathy is a sprue-like disease, which may manifest as a severe malabsorption syndrome with nutritional deficits and cachexia. The authors report a case of a 33-year-old Afghan man, who presented to the emergency department due to chronic watery diarrhea and severe malnourishment. He had been previously misdiagnosed with celiac disease in his early adulthood; however, this was based on inconclusive findings. After a thorough diagnostic workup, the final diagnosis of common variable immunodeficiency enteropathy with symptomatic norovirus infection of the gut was obtained during his prolonged hospitalization. A slow but progressive improvement was observed with immunoglobulin replacement therapy, corticotherapy, and ribavirin treatment. This is a noteworthy case of a rare malabsorption disorder, and it reviews important aspects concerning the differential diagnosis of small bowel villous atrophy of unknown etiology, as well as gastrointestinal manifestations of common variable immunodeficiency disorder.