Category:Mucosal immunity

Mucosal immune systems are targeted to be proactive and avoid inflammation.

Antigen capture

 * 1) Transcytosis through M cells
 * 2) Transport of Ab-coated particles by Fc receptor-mediated binding
 * 3) Through gaps when cells die by apoptosis
 * 4) Capture through dendrite extensions
 * 5) Uptake through goblet cells
 * 6) Macrophages/DCs cross epithelial layer to directly sample

Immune response to commensals
Commensals normally generate a tolerant response.

DCs may present commensal Ags in an immune-suppressive environment (presence of IL-10, TGF-β).

Under absent or reduced danger signals, DCs will initiate a T reg response.

Immune response to pathogens
When pathogens have breachd the epithelial barrier and are replicating in the lamina propria, danger signals will be generated.

Stronger TLR/danger signals trigger DC maturation. DCs migrate to mLN or local LN where they activate T cells.

Immune response to food antigens
Food Ags alone should not elicit danger signals (not PAMPs), thus don't usually induce an inflammatory or antibody response. Food normally is broken down into amino acids/sugars/lipids, and would not normally elicit a T cell response.

If sampled in the absence of danger signals, a tolerogenic response may be induced. DCs uptake food Ags in the LP, migrate to mLN and present Ag to T cells. DCs drive T cell differentiation into FoxP3+ T regulatory cells. Tregs actively suppress immune responses to food Ags through the secretion of IL-10.