L1: Intro to the immune system Flashcards
what is innate immunity ?
Innate immunity is a non specific defence mechanism that a host uses immediately or within several hours after exposure to antigen
Barriers to entry?
tears - lysozymes stomach- PH gut- microbiome epithelia respiratory tract (removal of particles) sneezing, skin
Describe the innate immune system response
inflammation, complement activation, phagocytosis
Stages of the immune response?
- local infection - penetration of the epithelium (skin, mucous membranes) Activates innate immune system. 2. pathogen infects local tissues. Innate immune system releases macrophages, neutrophils etc. 3. infection spreads to the lymphatic system. Immune cells and pathogens enter lymph nodes where APC present pathogen antigens to T and B cells. 4. activation of the adaptive immune system
acute phase proteins?
proteins by the liver. help pathogen recognition, inflammation and repair.
adaptive immune system components?
cellular: y8 T cells, NK, ILC, Th, B cells soluble: cytokines, chemokines, AB
barrier, soluble, and cellular components of the innate immune system?
barrier: epithelial soluble: complement, clotting cascade, acute phase, cytokines and chemokines cellular: dendritic, neutrophils, macrophages, mast cells, basophils, monocytes, NK cells, ILC (innate lymphoid cells), y8 T cells
cells of the adaptive immune system?
(INNATE- LIKE T CELLS) MAIT: mucosal associated invariant T cells. Cytokine secretion (pro inflammatory), mucosal patrolling (gut, airways) (ILT) NKT: recognise lipids in microbes, cytokine production. (ILT) y8 T cells: tissue specific immunity. cytoxicity, cytokine production. (ab T cells) CD4/Th: activate macrophages (ab) Tc/CD8+: recognise infected+ tumour cells. cytotoxicity, Cytokines *alpha beta T cells recognise specific ag to TCR Naive B cells + plasma cells *recognise ag via BCR
cells of the innate immune system along with descriptions?
(PHAGOCYTE) monocytes- monocytes from the blood mature into macrophages in tissues. Required for phagocytosis, cytokine production, tissue homeostasis, bacterial. (P) Dendritic- Antigen uptake in the periphery for antigen presenting cells. needed for cytokine production (P) neutrophil- circulate in blood, migrate quickly in inflammation for phagocytosis + bacterial. (DEGRANULATING EFFECTOR CELL) basophil- anti parasitic and allergic reactions (DEC) mast cells- in tissues. release granules e.g: histamine. inflammation + allergy (DEC) eosinophils- kill AB coated parasites by secreting granules.
clotting?
helps prevent blood loss and traps pathogen to prevent spread.
describe the adaptive immune system response
B cells activated, APC (dendritic cells) and T cells interaction. T cell proliferation and differentiation. Memory T cell and effector T cells form, B cell effector cells (plasma cells) form and memory B cells. AB production and emigration of lymphocytes from peripheral lymphoid organs. (T and B cells leave organs and enter the blood stream to carry out the immune response).
adaptive duration of response
days to weeks- long lasting.
organs of the immune system?
primary lymphoid organs: develop immature immune cells in the thymus and bone marrow. secondary lymphoid organs: where mature immune cells are exposed to antigens: lymph nodes (drain from tissue) + spleen (drain ag from blood), MALT (drain ag from gut). antigens are picked up by dendritic cells or carried in lymphatic fluid, to the secondary lymphoid organs. tertiary lymphoid organs: where IR occurs. SPLEEN: has B, T, macrophages. initiate innate and adaptive response. MALT: peyers patches, appendix, tonsils. gen of B cells producing igA AB ( good for viruses esp for mucosal infections) lymph nodes: site of maturation and differentiation of adaptive immune response.
problems with the immune system in infection, cancer, autoimmunity and organ rejection + immunotherapies?
INFECTION: innate immune response fails. immunotherapy involves targeting viruses and producing antibodies. CANCER: Tc and NK cells are exhausted due to metabolic competition with tumour cells. Immunotherapy involves: immune checkpoints inhibitors- drugs that block the inhibitory signals of Tc and NK and so regain the ability to attack cancer cells. since Tumour cells deplete nutrients for Tc and NK, target their metabolic pathways. AUTOIMMUNITY: body recognises self antigens as foreign. Immunotherapy: cytokine blockers to reduce inflammation. T and B cell modulation and immune checkpoint modulation. ORGAN REJECTION: T cells recognise donor antigens as foreign. Immunotherapy: suppress T cells. reduce inflammation.
what cells would be involved in fighting off viruses vs helminths?
VIRUS: NK, Th, Dendritic, macrophages PARASITES: Eosinophils, Basophils, Mast cells, Th,B cells, ILCs. *B cells produce antibodies, particularly IgE, in response to helminths (parasitic worms). These antibodies bind to the parasites and help recruit immune cells like eosinophils and mast cells, which release toxic substances to kill or expel the parasite.
