Lecture #1 Flashcards
Microbiota and microbiome
Microbiota: “the extended self” a community of symbiotic microorganisms living in the human body.
Microbiome: the collective genome of these micro organisms
How many immune cells per day does the boone marrow produces?
1-2*10^6
Immunological synapse
The interaction between an APC and a lymphocyte
Blast transformation
When a lymphocyte is activated by an immunological synapse and antigen binding it alters its cell morphology
(nucleus and cytoplasm increase, protein synthesis is activated)
Clonal selection theory
Cells of the recirculationg lymphocyte pool have specific receptors. If they encounter the specific antigen they will stop migratng and be activated .
Upon activation they will proliferate to form a colony of several thousands cells, all of which express the receptor with the same specificity.
Instruction theory
In the past it was thought that one lymphocyte have many receptors, each suitable for a specific different antigen, and if an antigen encounters the cell and had a good match to one of the receptors, the synthesis of this receptor was triggered.
Cells of the innate immune system
Macrophages, neutrophils, mast cells, NKC, immature DC, innate lymphoid cells
Phases of lymphocyte maturation
- Lymphocyte repertoir is generated in the bone marrow and thymus
- Activation and blast transformation - upon Ag binding
- Central phase - differentiation and clonal expansion
- Effector phase
Regulatory cells of the immune system
Treg
Breg
immature DC
Th2
Effector cells of the immune system
Th1, Th17, B , mature DC, NKC, macrophages
Shared features of cytokines
- They exert their effects through membrane receptors (high affinity binding)
- Transitional effect due to short 1/2 life of their mRNA and due to negative feedback
- Functional redundancy “pleiotropic effect”
Ex many types of cells secrete IL6 and IL6 effects many types of cells - Antagonist, additive or synergistic effect
- Autocrine, paracrine or endocrine effect
Chemokines and chemokine receptors
Chemokines: family of small sytokines responsible to induce direct chemotaxis of nearby responsive cells
classified in to 4 subfamilies: CXC, CC, C. CX3C
C represents cysteine and X any other AA at the N’ terminus
Chemokine receptors: 7TM receptors (G proteins) usually Gq
Adipokines
Cytokine secreted from adipose tissue
Leptin, adiponectin, IL6, MCP1, PAI1, TNFalpha
TNF group
TNF alpha: Regulation of immune cells, fever, inflammation, apoptosis, inhibition of tumorigenesis and viral replication
TNF beta and gamma: Induction of inflammation and anti viral responses, development of secondary lymph nodes
IFN group
INF alpha: Produced by fibroblasts and monocytes, DC, inhibits the replication of viral genome
INF beta: Produced by fibroblasts inhibits the replication of viral genome
INF gamma: Pro inflammatory cytokine