Lecture 3 Flashcards
Neutrophils recreuited due to…
Vasolidation
Margination
Sticky cell wall
Dendritic cells
MHC class II molecules
Puts peptide(antigen) onto it’s surface, travels to regional lymph node, puts it in contact with lymphocyte which has matching receptors
Specific adaptive immunity
Defends against specific microbes and foreign substances
Invloves memory for previously encountered antigents
B and T lymphocytes
Must recognize the specific antigen to be activated
Helper T cells
Activate B and cytotoxic T cells
B cells
Transform into plasma cells to produce and secrete antibodies
Humoral response: With Antibodies and Complement
Cytotoxic T cells
Attack infected body cells, cancer cells, foreign cells
Cell-mediated response
Macrophage presents antigen to Helper T cell
Puts MHC class 2 molecules to find helper T-cells that have appropriate receptor/connector
Activates helper T-cell
B-cell needs…
Assistance from Helper T cell via release of cytokines for full activation of B-cells so they produce plasma cells which release antibodies and also memory cells
Activation of Helper T Cells
Specific Recognition
- MHC-II + Peptide - T cell receptor
Co-reception
-CD28 - B7
Cytokine Release from APC
-Stimulates
3 stages of adaptive immune response
1) recognition of an antigen by lymphocytes
2)Lymphocyte activation
3) Attack launched by the activated lymphocytes and their secretions
Humoral
B cells:
- transform into plasma cells and produce and secrete antibodies
- Use antibodies and Complement to kill
Helper T-cells are necessary for….
Activation of of B-cells to plasma cells
Activation of Cytotoxic T cells
APC presents antigen and finds B-cell and T-cell with right receptor on it’s surface to start the process… how does it recognize the antigen???
MHC-II molecule bears an antigen which has to be recognized by specific T-cell receptor on helper T cell
B7 - surface of dendtritic cell
CD28 on surface of T helper cell - makes sure we are activating the right cells
Checkpoint Inhibition - why 2 key mechanism is so important
All biological systems need a way to shut off their actions
Need displacement of CD28 from B7
Uses CTL4A or PD1 on T cell surface (It’ll outcompete binding of B7 and replace the binding)
That tells the cell that the threat is over (stop killing)
Anti-CTLA4
Used when someone has cancer, so cytotoxic T-cells keep killing
Activation of B cells in Secondary Lymphoid Organs
Helper T-cell divides
Gets receptors for particular antigen
These activate the B-cells
B cell needs…
Cytokines from helper T-cell AND its own recognition of the antigen to start multiplying and making plasma cells and antibodies
B cells can process and Present Antigen to a Helper T-cells
Will present a Class II MHC protein to a helper 2 cell
Serum Protein Electrophoresis
Lot of albumin
alpha 1 and 2
Beta and gamma
Increased amount of gamma-globulin (antibodies) means…
Body is fighting infection
Plasma Cell
Produce Antibodies
1 week lifespan
They jus make antibodies for a living
Antibodies (Immunoglobulins)
Y shape
4 polypeptide chains
2 identical heavy chains
2 identical light chains
Variable region (upper part of antibody) - both a piece of heavy and light chain
Antigen binding site - hypervariable
FAB region
Constant region - bottom part
Mostly heavy chain piece, some bit of light chain
Conserved by all antibodies of a class
5 classes of antibodies
Determined by constant region:
IgG - most abundant, cross placenta, mother to fetus
IgA - dimer, mucous areas, also present in breast mil
IgM - pentimer, produced first in an immune response, later replaced with IgG, activate the Complement cascade
IgD - found prenatally
IgE - allergic responses
Antibody-Mediated Immunity
Carried out by B cells
Undergo clonal selection to produce plasma cells secreting specific antibodies and memory cells that allow for a faster response if the antigen is seen again
Antibody - Actively or Passively Acquired
Active: person’s own immune system reponds to microbe Long - lasting protection - Memory cells are involved
Natural: Exposed to antigen by chance (e.g flu virus)
Artificial: Purposefully exposed to antigen e.g flu VACCINE
Passive: Person receives antibodies from another person or animal, temporary protection - No memory cells involved
Natural : IgG from mother to fetus across placenta, IgA in breast milk
Artificial: Receive serum containing antibodies from person or animal that has been vaccinated
Active Immunity
Resistance due to the body’s contact with microorganisms, their toxins or other antigenic components
General Principle of Active Immunity
Exposure to the antigenic substance results in an active immune response that induces formation of memory cells required for rapid effective response to future infections of that organism
Passive Immunity
Direct transfer of antibodies from one person to another
E.g fetus receives maternal IgG antibodies that cross the placenta
Breast fed children receive IgA antibodies in the mother’s milk
V important for infant bc their antibody-synthesis ability is low
Antibody Functions
Neutralizing Antigen
Neutralize an antigen, change the 3d shape of the bacteria by binding to the toxin, can prevent toxic from infection you
Bacterial toxin
Agglutinating Antigen
Glue the antigens together, antibody holds them together by 2 diff ends
LOL makes it easier for them to be phagocytosed
Precipitating Antigen
Precipitate antigen, bring things out of solution of fluids of body and hold them together, keep the antigen from performing it’s function
Activating complement
Complement in non-specific immunity can activate compliment c3B to bind to surface of a pathogen to help it be phagocytosed
C1 - first complement protein (inactive)
Bacteria finds matching antigen so C1 complement is activated
This sets of a cascade of activity that leads to the activation of other complements leading to the MEMBRANE ATTACK COMPLEX
- loss of content from that cell and death of that cell
Opsonization
If antibody is specific to microbe it will bind to it and make it more visible to phagocytes
Phagocyte has receptors to Fc part of the anitbody molecule, Fc is the handle, variable region has binding event with antigen, non-specific effect of antigen
Antibody dependent Cellular Cytotoxicity via cytotoxic t cells
Rate of Antibody Production following initial exposure to an antigen and subsequent exposure to the same antigen
Increase rate and number of antibodies quickly after 1st antigen injection
2nd antigen injection causes crazy spike in antibody concentration
much longer lasting (that’s immunization)
