Secondary hypogammaglobulinemia in adults-A large retrospective cohort study

BACKGROUND AND OBJECTIVE

IgG replacement therapy (IgG-RT) has radically changed the clinical evolution of primary immunodeficiencies, yet the information regarding secondary hypogammaglobulinemia (SHG) is insufficient or conflicting. We aim to describe clinical features, evolution and treatment of SHG patients in our center.

METHODS

Dynamic retrospective cohort between January 2001 and July 2021 of adults with gamma globulin fraction <0.6g/dL in a serum protein electrophoresis and a coincident decrease of IgG levels - with a disease-related SHG or treatment that reduces serum immunoglobulins.

RESULTS

We included 1012 patients with SHG with a median follow-up of 5 years (IQR 2-8). Hematological diseases were identified in 95% of the patients and 61% received drugs related to SHG. Sixty five percent had more than one etiological factor associated with SHG. Infectious diseases were present in 69% of the patients, 48% had respiratory infections and 17% had severe infections. There was statistical association between respiratory and severe infections with multiple myeloma (MM), lymphoma and rituximab. MGUS had less infections and death compared with other etiologies. IgG-RT was indicated in 18.7% of the patients and 4.6% received it for more than 6 months with variable intervals. Among the latter group, there was a significant reduction of all-type infections and respiratory infections with IgG-RT (p<0.001), and it was consistent with similar findings in lymphoma, MM and all IgG levels subgroups.

CONCLUSION

SHG was associated with more than one etiological factor and a high frequency of infections. IgG-RT indication was irregular yet still effective. It is relevant to consider IgG levels screening, monitoring and accurate indication of IgG-RT.

[Management of hypogammaglobulinemia]

Hypogammaglobulinemia (hypoγ) is defined as a serum IgG level < 7 g/L. It is most often detected on serum protein electrophoresis. Given the existence of transient hypoγ, its persistence should be checked at distance, preferably by requesting a blood test for IgG, IgA and IgM, which will be needed to characterize a possible primary immune deficiency (PID). In the case of association with a monoclonal component, the first step is to look for a cryoglobulin causing a false hypoγ. Otherwise, the etiological investigation is dictated by the clinical examination. For example, the notion of chronic diarrhea should lead to a search for an enteropathy causing a digestive loss of gammaglobulins (an ambiguous situation because some DIP can be complicated by an enteropathy). In the absence of an obvious explanation, a secondary cause must first be ruled out (secondary immune deficiencies are 30 times more common than PID). The first simple test to perform is 24-hour proteinuria, coupled with urinary protein electrophoresis, to rule out 2 diagnoses: nephrotic syndrome and light chain myeloma. Subsequently, blood immunophenotyping looking for a circulating B clone is recommended, allowing the investigations to be directed towards a lymphoid hemopathy. Drug-induced hypoγ may also be suspected if certain drugs such as corticosteroids, anti-epileptics or immunosuppressive agents (especially anti-CD20) are taken. The profile of a drug-induced hypoγ is different from that of a DIP: it is rarely profound, the IgA level is preserved and there is no deficit in switched memory B lymphocytes. Finally, a thoracoabdominal CT-scan will help to rule out a thymoma and identify a deep tumor syndrome. If all these tests are normal, a PID is suspected, the leader of which in adults remains the common variable immunodeficiency, which is the most frequent symptomatic PID in adults.

Chronic hypogammaglobulinemia after allogeneic stem cell transplantation and their treatment with subcutaneous immunoglobulin in pediatric patients

INTRODUCTION

Hypogammaglobulinemia in the first months after allogeneic hematopoietic stem cell transplantation (HSCT) is common in paediatric patients. During this phase, replacement therapy with human immunoglobulin must be administered parenterally to prevent infections. In some cases, this hypogammaglobulinemia persists over time, which forces further treatment when the patient is usually no longer a carrier of a central line, making them ideal candidates for subcutaneous replacement therapy. There is little published literature describing the use of this method in paediatric patients undergoing HSCT, widely described in replacement treatment in children with primary immunodeficiencies with very good results.

PATIENTS AND METHODS

An observational, descriptive, longitudinal and retrospective study is carried out. During the years 2008-2019, we evaluated all paediatric patients undergoing HSCT in our center with persistent chronic hypogammaglobulinemia (for over a year). The treatment phase with intravenous immunoglobulin (Privigen®) and the first four years of treatment with subcutaneous immunoglobulin (Hizentra®) are evaluated using a questionnaire.

RESULTS

During the years 2008-2019, 175 patients underwent HSCT, 143 (82%) of whom exceeded three months after transplantation. Three (2%) of them had persistent hypogammaglobulinemia. All three share factors described in the literature involved in immune reconstitution. After analysing the questionnaire, it is observed that switching from intravenous to subcutaneous gammaglobulin has involved a great improvement in their quality of life.

CONCLUSIONS

The origin of chronic hypogammaglobulinemia in our patients shows different factors and cannot be attributed to a single cause. Due to the limited number of patients no conclusions can be drawn at the population level. We have been able to observe that replacement treatment with Hizentra 20% has been as effective as the intravenous administration without evidence of an increase in bacterial infections. Furthermore, it has also led to an improvement in quality of life and increased comfort, as the patients themselves have stated.

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.