Limited Innovations After More Than 65 Years of Immunoglobulin Replacement Therapy: Potential of IgA- and IgM-Enriched Formulations to Prevent Bacterial Respiratory Tract Infections

Abstract

Patients with primary immunoglobulin deficiency have lower immunoglobulin levels or decreased immunoglobulin function, which makes these patients more susceptible to bacterial infection. Most prevalent are the selective IgA deficiencies (~1:3,000), followed by common variable immune deficiency (~1:25,000). Agammaglobulinemia is less common (~1:400,000) and is characterized by very low or no immunoglobulin production resulting in a more severe disease phenotype. Therapy for patients with agammaglobulinemia mainly relies on prophylactic antibiotics and the use of IgG replacement therapy, which successfully reduces the frequency of invasive bacterial infections. Currently used immunoglobulin preparations contain only IgG. As a result, concurrent IgA and IgM deficiency persist in a large proportion of agammaglobulinemia patients. Especially patients with IgM deficiency remain at risk for recurrent infections at mucosal surfaces, which includes the respiratory tract. IgA and IgM have multiple functions in the protection against bacterial infections at the mucosal surface. Because of their multimeric structure, both IgA and IgM are able to agglutinate bacteria efficiently. Agglutination allows for entrapment of bacteria in mucus that increases clearance from the respiratory tract. IgA is also important for blocking bacterial adhesion by interfering with bacterial adhesion receptors. IgM in its place is very well capable of activating complement, therefore, it is thought to be important in complement-mediated protection at the mucosal surface. The purpose of this Mini Review is to highlight the latest advances regarding IgA- and IgM-enriched immunoglobulin replacement therapy. We describe the different IgA- and IgM-enriched IgG formulations, their possible modes of action and potential to protect against respiratory tract infections in patients with primary immunoglobulin deficiencies.

IgA: Structure, Function, and Developability

“…Besides, oral administration of SIgA/M prior to intragastric S. typhimurium challenge is sufficient to protect mice from infection [196]. Despite the studies showing the potency of these IgA antibodies to prevent bacterial infections, all the existing immunoglobulin preparations used clinically for replacement therapy contain only IgG [197].…”

Multi-Micronutrient Supplementation and Immunoglobulin Response in Well-Fed Firefighters

“…It is described that intensive exercise triggers the release of large amounts of autoantigen [5], which can promote serum immunoglobulin increase [25] or decrease [26], depending on exercise type. While 2 hours of intensive judo induced an increase in serum IgG ▶table 3 IgG, IgA, and IgM for the supplemented (SUP) and placebo (PLA) groups before and after the training period.…”

“…IgA is the most abundant immunoglobulin in the mucosal system (main functions: agglutination and antiviral capacity). They are crucial components of humoral immunity, with pathogen neutralization and opsonisation functions occurring during primary and/or secondary antibody responses [2][3][4][5][6]. They also regulate cellular cytotoxic activity via sensitisation of natural killer cells, phagocytes, and mast cells, and promote inflammatory responses and clearance of immune complexes via activation of the complement system [2,6].…”

Focus on Chronic Variable Immunodeficiency for Primary Care Practitioners, the Gatekeepers to Optimal Health Outcomes for Primary Immunodeficiency Syndromes

“…In fact, some antibody deficiencies do not benefit from IgRT at all. A review of commercially available products revealed that IgA and IgM, both of which have much shorter half-lives than IgG, are not material components of IgRT, making them ineffective for selective IgA or IgM deficiencies [60]. At the same time, the paucity of IgA and IgM in commercially available IgRT was reported to underlie continued susceptibility to certain types of infections for those with CVID.…”