Subclass distribution of salivary secretory immunoglobulin A antibodies to oral streptococci

Abstract

The ability of specific secretory immunoglobulin A (S-IgA) antibodies to inhibit bacterial colonization of mucosal surfaces may be neutralized by the activity of bacterial IgAl proteases. Because of the resistance of the IgA2 subclass to these enzymes, the biological effect of IgAl proteases in vivo may depend on the subclass distribution of the bacterium-specific antibodies. We have estimated the subclass distribution of S-IgA antibodies in saliva samples from 13 individuals against IgAl protease-producing (Streptococcus sanguis and Streptococcus oralis) and nonproducing (Streptococcus gordonii and Streptococcus mitis bv. 2) oral streptococci. IgAl was found to be the predominant subclass of antibodies against these four bacteria in most of the saliva samples, corroborating previous data suggesting a role of IgAl proteases in plaque formation. However, variation in the subclass distribution of S-IgA antibodies against the same strain was observed. In one individual, IgA2 was the predominant subclass of antibodies against all four streptococci and of total salivary S-IgA, pointing to the possible significance of genetic variations. The study also addresses methodological problems related to the quantitation of salivary antibodies by solid-phase immunoassays.

Allergen‐reactive antibodies are found in nasal fluids from patients with birch pollen‐induced intermittent allergic rhinitis, but not in healthy controls

“…Nunc polystyrene microplates (code, 269620) were used as solid phase throughout and proteins for coating were incubated at 5 μg/ml in 10 mM Tris buffered saline, pH 7.5 containing 0.1% sodium azide (TBS) in volumes of 100 μl at room temperature overnight. The TBS supplied with 0.15% Tween 20 (TBST) served as combined washing and blocking solution and as diluent for unknowns, standards, antibody reagents, and alkaline phosphatase conjugates, all of which were incubated at room temperature for 4 h. Pilot experiments showed that TBST used in this way, with the type of plates employed, prevented background reactions that may arise from nonspecific binding of test sample Igs and other postcoating reagents to the plate material (16). Optimal dilutions of commercial antibodies (from DAKO, Glostrup, Denmark, unless otherwise stated) were determined in pilot experiments.…”

“…Concerning the individual assay protocols, total IgA and IgG were quantitated by sandwich ELISA using isotype‐specific rabbit antibodies for coating and enzyme‐conjugated verions of the same antibodies for detection (third layer). Secretory‐IgA purified from human colostrum (16) served as standard in the IgA assay whereas isotype standards for the IgG assay were obtained from DAKO. Birch allergen‐reactive IgA and IgG antibodies in nasal wash were quantitated in gravimetric units (ng/ml) as described (17).…”

IgG and IgA subclass mRNA-bearing plasma cells in periodontitis gingival tissue and immunoglobulin levels in the gingival crevicular fluid

“…ELISA assays were broadly based on sandwich assays previously developed [35][36][37][38][39]. However, these were substantially modified to increase sensitivity and thus detectability in GCF.…”

In vivo cleavage of immunoglobulin A1 by immunoglobulin A1 proteases from Prevotella and Capnocytophaga species

“…Human dimeric IgAl (Kah) was isolated from the serum of a patient with multiple myeloma as previously described (5). The IgAl preparation was devoid of IgG and IgM and contained less than 5% IgA2, as tested by ELISA (2).…”

“…Fragments of IgAl (Fab, Fc, or Fc2.SC), indicating in vivo activity of IgAl proteases, have been demonstrated in intestinal fluid (25), in vaginal secretions of women with gonococcal infection (3), in cerebrospinal fluid from patients with H. influenzae meningitis (12), in nasopharyngeal secretions from children (19,38), in saliva and on the surface of dental plaque bacteria (1,2). Lack of evidence of in vivo activity of IgAl proteases from Prevotella and Capnocytophaga has been one of the reasons why their significance in the subgingival microenvironment so far has been speculative.…”