Unexpectedly high levels of some presumably protective secretory immunoglobulin A antibodies to dental plaque bacteria in salivas of both caries-resistant and caries-susceptible subjects

Abstract

The role of salivary antibodies in protection against cariogenic bacteria is actually a matter of debate. Correlation between caries experience and naturally occurring antibodies was extensively investigated. Comparison of salivary antibodies from 21 caries-resistant and 22 caries-susceptible subjects was carried out by using a new quantitative method. Secretory immunoglobulin A (S-IgA) antibodies to Streptococcus sobninus and Streptococcus sanguis cells were detected in all salivas and at similar levels in both groups. When assayed with two major antigens from S. sobrinus, i.e., protein antigen VI/I and cell wall carbohydrates, only specific activities of antibodies to the protein component were increased (P < 0.001), but this occurred unexpectedly in the caries-susceptible group. Western blot (immunoblot) analysis with the culture supernatant and cell wall proteins from S. sobrinus showed the same antibody specificity in both groups. No selective increase of the protease-resistant S-IgA2 subclass was found, and avidities of antibodies to both antigen I/I and cell wall carbohydrates were similar. Our results demonstrate that naturally induced S-IgA antibodies against S. sanguis, S. sobninus, and the major antigens of the latter are not sufficient to inhibit caries development.

Systemic and Secretory Humoral Immunity in the Normal Human Vaginal Tract

“…The purity of this standard was controlled by complete lack of precipitation (sensitivity -^ 2/ig/ml) by double diffusion with soluble jacalin. This method provided IgA2/total IgA ratios of 10% for the serum [20], 30% for the saliva [16], and 20-30% for the colostrum, in agreement with the figures generally admitted.…”

“…3B). SIgA Abs of this specificity are induced by chronic oral stimulation, and can be detected at high levels in most human salivas [16]. Their low specific activity in the vaginal fluid could be explained by a certain degree of variation between different sites ofthe MALT [12].…”

“…SIgA and SlgM were measured by asymmetrical ELISA, using the Abs to a or ^ chains for capture, and the labelled anti-SC as second Ab. Igs bound to mucus were investigated in the pellet of vaginal fluids after acidic dissociation, as already described for saliva [16].…”

“…The purified toxoid was kindly provided by B. Bizzini (institut Pasteur, Paris, France). The carbohydrates were prepared from a cariogenic strain [16] by nitrous extraction, according to the method of Swanson et al [17]. After blocking for 2 h at 37X and three washes with PBS-Tween 20 (0.05% v/v), vaginal fluids were incubated overnight at 4''C.…”

Physical and Chemical Aspects of Saliva as Indicators of Risk for Dental Caries in Humans

“…Twenty-two studies examined the relation between salivary immunoglobulins and caries status. 12,16,29,30,45,46,50,[73][74][75][76][77][78][79][80][81][82][83][84][85][86][87] The levels of specific sIgA showed a modest inverse relationship with caries risk, and the literature is nearly equally divided for and against an anticaries role of specific sIgA. Seven studies reported an inverse relationship between specific sIgA antibodies in saliva (for example, anti-S. mutans sIgA) and caries status, 74,79,[81][82][83][84][85] while two studies reported that caries was related to increased levels of specific sIgA 80,86 and five studies reported no relationship between specific sIgA immunoglobulins and caries.…”