Question

Mucous membranes are weak areas (from an infection standpoint) on the human body. List and describe the benefit(s) (and don’t say anything like “it helps prevent the bacteria from causing disease”, be specific) of at least 3 mechanisms that the body utilizes to prevent pathogens from gaining access to the body through these mucous membranes

Answer 1

1. Mucosal Immunity through secretory IgA:

They are produced by plasma cells in the lamina propria adjacent to mucosal surface. It is endocytosed in the epithelial cells when it binds to to its receptor present on basolateral side. This receptor- IgA complex passes through the cell and is secreted into the luminal side of epithelial cell. Proteolysis of receptor allows IgA to diffuse into the lumen. They bind to mucous membrane present on luminal side of epithelial cells and trap antigen in the mucous membrane and clear them peristaltically.

2. Mucosal Immunity through MALT.

MALT stands for mucosa-associated lymphoid tissue. They contain small aggregation of lymphocytes called lymphoid follicles. They can be large and confluent. When encountered by antigen, lymphocytes may kill, opsonize, precipitate or neutralize the antigen.

Examples: Tonsils in Pharynx, Peyer's patches in ileum, MALT in appendix, etc

3. Lymphatics from mucosa connected to regional lymph nodes also helps in eliminating pathogens. Example: Mucosa of Intestine is connected to Mesenteric lymoh nodes.

Moreover, mucosa provides a physical barrier as well. It also has cells of innate immunity which also play a major role in preventing pathogen from gaining access to body through mucous membranes.