Immunity Flashcards
Muscosa is vulnerable due to
Fragility and permeability
Requires effective defence mechanisms, portals of entry for non-pathogenic anitgens
Intestinal lymphocytes are found
- In organised tissues where immune responses are induced
2. Scattered throughout intestine where they carry out effector functions
Peyer’s patches are found
in the small intestine
Peyer’s patches are covered by an epithelial layer containing
Specialised M cells
Characteristic of M cells
Ruffles
How do M cells work
Take up antigen by endocytosis and transport to dendritic cell which activates T cells
Adaptation of dendritic cells
Can reach through epithelial layer to capture antigen from lumen
2 compartments of mucosal immune system
- Immune cells of lamina propria
2. Immune cells of epithelial layer
T cells enter Peyer’s patch from
blood vessels
How do T cells in Peyer’s patch work
When activated, they drain through lymph nodes to thoracic duct and return to gut via bloodstream
Paneth cells secrete
Defensins
Where are Paneth cells found
SI not large
IgA in GI tract
80%
IgM in GI tract
15%
IgG in GI tract
5%
IgA
Can neutralise pathogens and toxins
IgA internalised in endosomes
Export toxins and pathogens from lamina propria while being secreted
Special T cells in gut
IEL’s
Intraepithelial lymphocytes
IEL’s
80% CD8+
- Virus infects mucosal epithelium cell
- Activated IEL kills epithelial cell by Fas dependant pathway
Infectious disease
Infection crosses mucosa and fuses to dendritic cells which shuttle virus to lymph nodes
Infection spreads to CD4+ lymphocytes
Viral infected cells go into bloodstream and disseminate across body
Primary Immunodeficiency
Selective IgA deficiency CVID XLA CGD SCID
Selective IgA deficiency
Aysmptomatic
Recurrent sino-pulmonary infection (coeliac disease X10)
Common Variable Immunodeficiency
Recurrent sino-puomonary and GI infections (low IgM+G)
X linked Agammaglobulinaemia
Sino-pulmonary and GI infetcions
Devastating entervoviral infection (no B cells)
