dental caries & iga

8/3/2019 Dental Caries & IgA

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Principal immunoglobulinHumoral element in secretoryimmune systemHas a neutralizing component to

prevent attachment and adherence of oral bacteriaSIgA adheres selectively to M cells inintestinal Peyers patches, thusmediating the transepithelialtransport of the Ab molecule from theintestinal lumen to underlying gut-associated organized lymphoid tissue


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IgA functions at three anatomical levels inrelation to mucosal epithelium:

1) luminal SIgA Ab prevents adhesion and entry of

Ag into the epithelium;2) IgA Ab in the lamina propria binds and excretesAg to the lumen; and

3) IgA Ab in transit through the epithelium caninhibit virus production or neutralizeproinflammatory Ags .

An additional property of IgA is its inability totrigger the release of inflammatory mediatorsthrough receptors specific for its Fc domain


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At Birth, IgA not detectable4-6 wks levels rapidly riseIgA1 dominates, by 20 wks IgA2 increases to adult

levels.Early childhood: lysozyme and salivary peroxidase areat adult levelsMUC5B dominates over MUC7 from 1mo-1yr

Antimicrobial peptides:Beta-defensin-3Cathelicidin LL37Alpha-defensins 1,2,3HNP1-3 were greater in cavity free children


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Sterile at Birth S. mitis and S. oralis very early (within 24

hours) S. Sanguis by 9 months of age S. mutans and S. sobrinus 18-24 monthswindow of infectivity


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Increase resistance of teeth (e.g., fluoride,sealants)

Improve diet Alter microflora mutant strainsmechanical (remove niche)antimicrobial/antibioticalter salivary components - specific and non-specific


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GALT: gut associated lymphoreticular tissueOthers: BALT - bronchial

NALT -nasal DALT -ductal SALT - salivary


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Inhibition of adherence of microorganisms onepithelial surfaces (or teeth, i.e., AgI/II)

Neutralization of toxins or enzymes (e.g.,GTF) Viral neutralization (e.g., polio virus) Antigen trapping and antigen exclusion Interaction of S-IgA with non-specific defensemechanisms (e.g., mucins, lactoferrin,

lysozyme,lactoperoxidase)


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Immunologic Means to ObtainCaries Immunity

1. Natural Immunity2. Active immunity Local immunization Systemic immunization Oral/Mucosal Immunization 3. Passive Immunization


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Natural Immunity to Dental CariesMaternal Protection

Ontogeny of Mucosal Immunity Natural Caries Immunity


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Unique Aspects of InfancyTeeth are erupting

Oral cavity is being colonized Breast feeding is discontinued Immune system is developing


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Obstacles Encountered in DemonstratingCaries Protective Role of IgADental caries is a chronic, slow process

Dental caries may not be active when antibody activity is assessedAbsorbance of antibodies by oral micro -organismsDetermination of local antibodies in the microbial environmentCross reacting antigens between cariogenic andnoncariogenicorganisms


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Why dont some individuals respond to theobvious challenge?

Do individuals with caries and decreasedantibodies have the ability to respond?Can the response in non -responsiveindividuals be induced?


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Identification of virulence antigens of S. mutansLack of understanding of the mechanism of immune

protection

Mechanisms involved in the induction and regulation of protective immunityPossibility of immunopathological complications to

immunizationApproval to test candidate vaccine in young population

dental caries & iga

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