Recognition of Gram-positive Intestinal Bacteria by Hybridoma- and Colostrum-derived Secretory Immunoglobulin A Is Mediated by Carbohydrates

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

“…We have established that covalent, disulfide bridge-mediated binding between plasma pIgA and hSC occurs, further demonstrating the efficiency of the in vitro assembly process. Similar results were observed for SIgA recovered from human colostrum (13,33) and may be due to the reduced capacity of SC in SIgA2 to form covalent complexes, as compared with SIgA1 (27). Alternatively, in rodent species with a single IgA subtype, partial covalency is observed systemati- cally (34) and may reflect intrinsic exchange between disulfide bonds in the ␣ chain and domain 5 in SC (19).…”

“…This material is devoid of J chain and has been reported in analyses of hybridoma cell culture supernatants (15), in samples of bile and feces (16), in CHO cell line clones expressing pIgA (20), and even in human colostrum (13).…”

“…Colostrum-derived hSC (hSCcol) was obtained as described (13). Mouse IgAC5 specific for S. flexneri LPS serotype 5a and recombinant mouse SC (mSC) were produced and purified as described (12,14).…”

Role of secretory IgA in the mucosal sensing of commensal bacteria

“…23 Strikingly, interaction between commensals and SIgA is not only antigen-driven, 24 as natural polyreactive SIgA and Fab/Fc-independent, glycan-mediated binding are also likely to contribute substantially to this process. 25 The involvement of SIgA in the numerical control of the gut microbiota was further confirmed in germ-free or mono-associated mice. 26,27 In IgA-deficient mice, systemic antibody responses against commensal species are increased, 28,29 arguing for control of transepithelial dissemination by SIgA.…”

The Role of Secretory Immunoglobulin A in the Natural Sensing of Commensal Bacteria by Mouse Peyer's Patch Dendritic Cells

“…Strikingly, interaction between commensals and SIgA is not only antigen-driven, as natural polyreactive SIgA isolated from human colostrum and mouse hybridomas was shown to associate with commensals in a Fab/Fc-independent, glycanmediated manner (23). Moreover, complexes made of such SIgA and commensal bacteria potentiate epithelial cell responsiveness to bacteria in vitro (24). The combination of these mechanistic data led us to speculate that SIgA may govern the mucosal sensing of commensals by facilitating communication with partners of the underlying immune system.…”