Correlation of hypogammaglobulinaemia with proteinuria, and the relationship between hypogammaglobulinaemia and infection in active lupus nephritis

Salivary IgA subtypes as novel disease biomarkers in systemic lupus erythematosus

Introduction

Immunoglobulin A (IgA) is the main antibody isotype in body fluids such as tears, intestinal mucous, colostrum, and saliva. There are two subtypes of IgA in humans: IgA1, mainly present in blood and mucosal sites, and IgA2, preferentially expressed in mucosal sites like the colon. In clinical practice, immunoglobulins are typically measured in venous or capillary blood; however, alternative samples, including saliva, are now being considered, given their non-invasive and easy collection nature. Several autoimmune diseases have been related to diverse abnormalities in oral mucosal immunity, such as rheumatoid arthritis, Sjogren's syndrome, and systemic lupus erythematosus (SLE).

Methods

We decided to evaluate the levels of both IgA subtypes in the saliva of SLE patients. A light chain capture-based ELISA measured specific IgA1 and IgA2 levels in a cohort of SLE patients compared with age and gender-matched healthy volunteers.

Results

Surprisingly, our results indicated that in the saliva of SLE patients, total IgA and IgA1 subtype were significantly elevated; we also found that salivary IgA levels, particularly IgA2, positively correlate with anti-dsDNA IgG antibody titers. Strikingly, we also detected the presence of salivary anti-nucleosome IgA antibodies in SLE patients, a feature not previously reported elsewhere.

Conclusions

According to our results and upon necessary validation, IgA characterization in saliva could represent a potentially helpful tool in the clinical care of SLE patients with the advantage of being a more straightforward, faster, and safer method than manipulating blood samples.

Practical guidance for the diagnosis and management of secondary hypogammaglobulinemia: A Work Group Report of the AAAAI Primary Immunodeficiency and Altered Immune Response Committees

Secondary hypogammaglobulinemia (SHG) is characterized by reduced immunoglobulin levels due to acquired causes of decreased antibody production or increased antibody loss. Clarification regarding whether the hypogammaglobulinemia is secondary or primary is important because this has implications for evaluation and management. Prior receipt of immunosuppressive medications and/or presence of conditions associated with SHG development, including protein loss syndromes, are histories that raise suspicion for SHG. In patients with these histories, a thorough investigation of potential etiologies of SHG reviewed in this report is needed to devise an effective treatment plan focused on removal of iatrogenic causes (eg, discontinuation of an offending drug) or treatment of the underlying condition (eg, management of nephrotic syndrome). When iatrogenic causes cannot be removed or underlying conditions cannot be reversed, therapeutic options are not clearly delineated but include heightened monitoring for clinical infections, supportive antimicrobials, and in some cases, immunoglobulin replacement therapy. This report serves to summarize the existing literature regarding immunosuppressive medications and populations (autoimmune, neurologic, hematologic/oncologic, pulmonary, posttransplant, protein-losing) associated with SHG and highlights key areas for future investigation.

Acquired low immunoglobulin levels and risk of clinically relevant infection in adult patients with systemic lupus erythematosus: a cohort study

OBJECTIVE

Infection is a leading cause of death in the SLE population. Low immunoglobulin levels might be a potential risk for infection. We aimed to assess whether acquired low levels of any type of immunoglobulin increase the risk of clinically relevant infection in adult patients with SLE.

METHODS

We compared adult SLE patients who had acquired any low immunoglobulin levels (IgA, IgM or IgG) for 2 years with patients with normal or high levels with respect to clinically relevant infection (defined as infections requiring intravenous or oral antibiotics) in a prospective cohort study. Group balance was achieved using propensity score adjustment, matching and inverse probability weighting. Primary analysis was time to event using Cox-regression modelling adjusting for potential confounders. Sensitivity analyses were conducted to examine several exposure and outcome definitions.

RESULTS

Patients with hypogammaglobulinaemia had longer disease duration, more lupus nephritis history, higher proteinuria and more accumulated damage. Low IgA level was associated with increased risk of clinically relevant infection [hazard ratio (HR): 2.24, 95% CI: 1.61, 3.12] while low IgG (HR: 1.15, 95% CI: 0.84, 1.59) or low IgM (HR: 0.95, 95% CI: 0.73, 1.23) was not. Low immunoglobulin recovery in the first year was 2.5% (11), second year 8.2% (36), third year 10.1% (44) and fourth year 18.4% (80), and 60% (263) of acquired hypogammaglobulinaemia recovered over 4 years.

CONCLUSION

The majority of acquired hypogammaglobulinaemia in adult patients with SLE is transient. Only low acquired IgA was associated with increased risk of infection among adult patients with SLE. Whether immunoglobulin replacement provides additional protective effect requires further investigation.

Immunoglobulin levels in systemic lupus erythematosus: A narrative review

Immunoglobulins play a fundamental role in the protection of the human body against internal and external threats. They also contribute to the immune system homeostasis and maintenance of self-tolerance. Hypogammaglobulinemia is occasionally encountered in routine clinical practice by rheumatologists. Low levels of immunoglobulins can occur as primary or secondary issues and may predispose patients to various forms of infection. However, the impact of the low immunoglobulin level abnormality varies with the underlying condition. In this narrative review, we shed light on the overall types and functions of immunoglobulins for clinicians. We discuss important principles of immunoglobulin measurements. We then consider the primary and secondary causes of low immunoglobulins with a special focus on hypogammaglobulinemia in patients with systemic lupus erythematosus (SLE).

Secondary immunodeficiencies with predominant antibody deficiency: multidisciplinary perspectives of Polish experts

At present, secondary immune deficiencies have become a clinical problem, recognized in different specialties. The aim of this paper was to increase awareness and support the need for screening at-risk populations. Secondary immune deficiencies result in variety of conditions, but not all of them require immunoglobulin replacement therapy, as specific antibody response might be preserved. Moreover, the management of secondary immune deficiencies vary between countries and different medical disciplines. This literature review presents the most common causes and clinical presentation of secondary immunodeficiencies with predominant impaired antibody production. We present diagnostic guidelines for patients at-risk, with an emphasis on the role of prophylactic vaccination as a treatment and diagnostic tool. This review considers the specificity and disparities of the Polish healthcare system and ultimately, suggests that management teams should include a clinical immunologist experienced in the treatment of humoral immunodeficiencies.

Immunoglobulin abnormalities are frequent in patients with lupus nephritis

Background

Hypogammaglobulinemia is a complication of B-cell targeting therapies (BCTT), used in vasculitis, rheumatoid arthritis and systemic lupus erythematosus (SLE). Since autoimmune diseases are associated with underlying and induced immune abnormalities, several societies recommend assessing immune function before and during rituximab treatment. In SLE, polyclonal hypergammaglobulinemia is the typical alteration of gammaglobulins, though hypogammaglobulinemia has also been reported.

Methods

This is a cross-sectional study describing immunoglobulin levels measured as part of routine care in patients with lupus nephritis, a group with multiple factors contributing to immunoglobulin abnormalities, including immune dysregulation, immunosuppression and nephrotic syndrome.

Results

Polyclonal hypergammaglobulinemia occurred in 15/83 (18.1%) patients. In contrast, low levels of immunoglobulins were found as follows: selective IgA deficiency 2/83 (2.4%), reduced IgG levels 7/83 (8.4%), reduced IgM 14/83 (16.9%). Only 1 patient required immunoglobulin replacement.

Conclusions

Immunoglobulin abnormalities are frequently found in lupus nephritis, ranging from polyclonal hypergammaglobulinemia to hypogammglobulinemia. Consequently, immunoglobulin levels should be assessed prior to commencing BCTT.