10.18.17 Immune System & Immunosuppressants Flashcards
What are the four primary organs involved in the immune system? What happens at each?
- Bone marrow: source of blood cells
- Thymus: T-cell maturation
- Spleen: hematopoietic organ, site of macrophage antigen presentation, antibody response
- Lymph nodes/vessels: lymphocytes (NKC, T, B-cells)
List three types of lymphocytes; what do they secrete?
B-cell (antibodies), T-cell (cytokines), NKC (cytokines)
List three types of granulocytes; which is most abundant?
Neutrophil (most abundant), eosinophil, basophil
Compare and contrast the innate vs. adaptive immunity: specificity, diversity, memory, time frame, cellular/protein components
INNATE: general molecular patterns (eg. wall), limited diversity, no memory, fast, cells=phagocytes, NKC, innate lymphoid cells, proteins=complement
ADAPTIVE: specific antigens, large diversity (V(J)D recombination), memory capable, slow (unless primed), cells=lymphocytes, proteins=antibodies
Describe the three types of phagocytes and their role:
- Monocyte–>macrophage: kill pathogens, antigen presenting cell (APC) and cytokine release
- granulocytes: lysozyme release
- dendritic cells: degrade pathogens, APC
During infection, list four steps/roles of a phagocyte:
chemotaxis, migration, ingestion and microbial killing
Macrophages and dendritic cells express _______ which recognize ______.
Pattern Recognition Receptors (PRR), Pathogen Associated Molecular Patterns (PAMP)
What are the three primary functions of the complement cascade?
- chemotaxis (c3a, c5a)
- opsonization (c3b coating)
- cell lysis (MAC complex c5b-9)
Compare and contrast humoral vs. cell-mediated immune response: microbe, responding lymphocyte, effector mechanism, transferred by, and function.
HUMORAL: extracellular microbes, B-cell, secretion of antibodies, transferred by serum, block and eliminate extracellular microbes
CELL-MEDIATED:
- phagocytosed microbe IN macrophage, Helper T (CD4)–>(MH II), transferred by Helper T, activate macrophage to kill phagocytosed microbes
- intracellular microbe (eg. virus), Cytotoxic T (CD8)–>(MHC I), transferred by Cytotoxic T, kills infected cells and eliminate reservoir of infection.
Which part of the antibody contributes to its variability?
Variable region
Name the mechanism for diverse binding selectivity in antibodies, B-cell and T-cell receptors.
V(D)J Recombination
What are the 5 immunuoglobulin types? Which is most common in allergic response? Plasma?
IgA, IgD, IgE, IgG, IgM (DGAME). IgE in allergic response; IgG, IgM in plasma.
List a few actions of antibodies
Agglutinization, opsonization, neutralization, antibody -dependent cellular cytotoxicity (mark cells for destruction), activation of complement, therapeutic uses (Herceptin/trastuzumab to treat breast CA)
Compare and contrast MHC I vs. MHC II: Cells present on, antigens bound, T cell associated.
MHC I: present on most cells, binds endogenous antigens to CD8 on Cytotoxic T cell.
MHC II: present ONLY on APC (phagocytes, NKC, etc), binds exogenous antigens to CD4 on Helper T cell.
What is the difference between MHC and HLA?
MHC (Major histocompatibility complex) is a large gene family involved in immune functions in different species.
HLA (Human leukocyte antigen) is the human version of MHC genes.
Why is HLA important in the immune response?
Identification of self from non-self, variable from person to person (like a barcode), responsible for tissue rejection in organ transplants
What two signals are required to activate a T-cell?
1) MHC + TCR (T-cell receptor) : dendritic cell presents antigen on MHC, the T-cell engages the MHC + antigen complex.
2) Co-stimulatory molecule and receptor (without this second signal, T cell activation stops or apoptosis occurs)
Give and example of a co-stimulatory molecule and receptor:
On APC: CD80/86
On T-cell: CD28
Cell mediated immunity begins with the bacteria being ‘eaten’ by ________, which presents antigens to helper T-cell with MHC class ___. Activated helper T-cells secrete ____ and also activate ____ cells to form Ab-producing ________. Other phagocytic cells, including NK, macrophage and cytotoxic T-cells to kill invaders.
Cell mediated immunity begins with the bacteria being ‘eaten’ by macrophages (APC) which presents antigens to helper T-cell with MHC class II. Activated helper T-cells secrete IL-2 and also activate B cells to form Ab-producing plasma cells. Other phagocytic cells, including NK, macrophage and cytotoxic T-cells to kill invaders.
Outline the steps T-cells take to induce apoptosis
1) Bind to MHC I + antigen complex on infected/diseased cell
2) Directed release of cytotoxic proteins (perforins, granzymes)
3) Recycle T-cell
An allergic reaction to a harmless antigen is known as ____________.
Hypersensitivity
Immunodeficiency is:
Inability to stop infection
Define autoimmune disorder
Immune system targets self-antigens
Azathioprine and mycophenolate are DNA-synthesis inhibitors. Describe their mechanism of action:
Azathioprine: purine analog, incorporates into replicating DNA and halts replication. It can also block the pathway for purine synthesis. Result: inhibit cell proliferation, especially fast-growing cells without method of nucleotide salvage (T, B-cells).
Mycophenolate: Inhibit inosine-5’-monophosphate dehydrogenase (IMPD). Result: control rate of de novo guanine (purine) synthesis in cell proliferation (T, B-cells).
