Human Plasma-derived Polymeric IgA and IgM Antibodies Associate with Secretory Component to Yield Biologically Active Secretory-like Antibodies

Abstract

Background: Production of SIgA or SIgM for therapeutic application remains an unsolved issue. Results: Human plasma-derived polyclonal, polymeric IgA and IgM associate with recombinant or colostrum-derived human secretory component to form digestion-resistant, functionally active SIgA-and SIgM-like molecules. Conclusion: SIgA and SIgM can be rebuilt ex vivo from plasma-derived IgA/IgM. Significance: This would enable development of SIgA/SIgM-based mucosal therapeutics.

Reconstituted Human Polyclonal Plasma-derived Secretory-like IgM and IgA Maintain the Barrier Function of Epithelial Cells Infected with an Enteropathogen

“…We found that plasma-derived purified pIgA and IgM can associate with a recombinant secretory component (SC) with a 1:1 stoichiometry and that this association delayed the degradation of pIgA or IgM by intestinal washes containing proteases. In addition to these essential biochemical features, we showed that pIgA and secretory-like IgA delayed damage to epithelial polarized Caco-2 cell monolayers induced by a virulent strain of enteropathogenic Shigella flexneri (29). However, how the plasma-derived Ab operates to block the bacterium and contributes to epithelial homeostasis was not addressed in this study.…”

“…Human Plasma pIgA and SIgA Abs Agglutinate Bacteria Lead to a Decrease of the Bacterial Load in Caco-2 Cell Monolayers and of Proinflammatory Cytokines/Chemokines-We demonstrated previously that human plasma-derived pIgA and reconstituted SIgA, but not plasma mIgA, significantly maintained Caco-2 cell intestinal epithelial monolayer integrity after O/N infection with S. flexneri by preventing the reduction of TER, the disruption of the tight junction network, and the detachment of filter-bound Caco-2 cells (29). However, the underlying mechanisms explaining protection were not addressed.…”

“…We established previously that human plasma-derived pIgA and IgM can be assembled into secretory-like Abs (29). However, how the various molecular forms of the Ab displayed differential protection was not evaluated at the cellular and molecular levels.…”

“…Mouse monoclonal SIgAC5 was obtained by combining, in vitro, 10 g of purified pIgAC5 molecules with 2.5 g of recombinant mouse SC. Association and characterization of SIgA and SIgM Abs were performed in PBS for 30 min at room temperature as described previously (29).…”

“…Preclinical and clinical studies have underscored the efficacy against various infectious agents of polyclonal IgM-enriched preparations administered by the systemic route (22)(23)(24)(25)(26). Similar to SIgA, SIgM can be seen as a valid candidate immunoglobulin for mucosal application, given its ability to bind antigens with strong avidity, its potential to ensure long term protection (27), its capacity to survive low pH conditions (28), as well as its resistance to proteases (29). We have demonstrated recently that human plasma can serve as a source of polyreactive, polymeric IgA (pIgA) and IgM to generate secretory-like IgA and IgM Abs, the natural molecular form found in secretions.…”