Kåre Tolo

Mucosal penetrability enhanced by serum-derived antibodies.

ALTERED mucosal penetrability for food constituents and microbial components probably underlies the pathogenesis of a variety of diseases occurring in mucous membranes and distant sites such as liver and joints1. The secretory immune system seems to be of major importance in mucosal exclusion of foreign material and is stimulated by topical antigens2. Conversely, parenteral immunisation almost exclusively gives rise to circulating antibodies which are chiefly of the IgG class. IgG is not a secretory immunoglobulin in man, monkey, rabbit and guinea pig3, and contradictory information has been published about the effect of parenteral immunisation on the absorption of antigen through mucous membranes. Moreover, a possible influence on the concurrent mucosal penetration of unrelated macromolecules has not been considered previously. We report here that although serum-derived antibody retards the penetration of corresponding antigen, it nevertheless causes impairment of the mucosal barrier. Induction of IgG antibodies may thus cause hazardous side effects by altering mucosal penetrability.

Enzyme-linked immunosorbent assay for human IgG, IgA, and IgM antibodies to antigens from anaerobic cultures of seven oral bacteria

Monocultures of 7 oral bacteria were grown anaerobically, and antigens were partially purified from the supernatant fluids by gel filtration. Isoelectric focussing showed that the antigen fractions contained PAS-positive material and proteins focussing between pH 3.5 and pH 5.5. Specific activity against the 7 antigen fractions was observed for IgG, IgA, and IgM in serum from patients with periodontal disease by means of enzyme-linked immunosorbent assay (ELISA). Conditions for antigen coating in ELISA were studied, and large variations with regard to optimal concentration were found among the 7 fractions. The ELISA readings were virtually unaffected by increasing the pH of the coating buffer from 5 to 9. Addition of sheep serum to the incubation buffer was disadvantageous as the serum showed moderate antibody activity to the 7 antigen fractions, and human serum apparently contained IgM antibodies to sheep IgG. Addition of 0.5% BSA improved the reproducibility of ELISA considerably, although the sensitivity was somewhat decreased.

Antigens released from four oral Bacteria in Periodontitis

Antigens fractionated from cultures of four oral bacteria were tested for binding of serum IgG, IgA and IgM from patients in early and established phase of periodontitis. Bacteroides gingivalis and A.actinomycetemcomitans released antigens that discriminated between serum from individuals with or without periodontitis. The discriminating antigens ranged from 10 to 43 kDa and included neutral sugar and protein but no lipids. Significantly increased levels of IgG and IgA antibodies to the antigens released from B. gingivalis were detected before bone loss was seen and predicted such disease progression.