Lecture 8-10 Flashcards
What is aquired or adaptive immunity?
The response of the body via lymphocytes to foreign invading organisms, etc. (Specific response)
Molecules that are identified as foreign and produce an immune response are called ________
Antigens
Antigens often posses repeating/reoccurring molecular groups called ______ which are observed in proteins and large polysaccharides.
Epitopes (The part of the antigen where the antibody binds to)
Where are lymphocytes primarily found?
Lymphocytes are found primarily in bone marrow, lymph nodes and lymphoid tissues throughout the body.
Lymphocytes (B and T) must go through an essential maturation/programming call “processing”, afterwards nearly all lymphocytes reside in the ___________.
Secondary lymphoid organs throughout the body
Where are T and B lymphocytes processed?
T-lymphocytes are processed in the Thymus prior and after birth.
B-lymphocytes are processed in the liver prior to birth and then to bone marrow after birth.
T or F? T-lymphocyte develops reactivity to multiple antigens.
False, T-lymphocyte develops specific reactivity to one antigen.
In the thymus, T-lymphocytes are “checked” to ensure that they do not respond to any of the body’s own ____ or “____”.
tissues ; “self-antigens”
T or F? More than half of the T-lymphocytes make through the “checking” process.
False, t-lymphocytes are exposed to virtually all self-antigens and any that react are destroyed and/or phagocytized, (can be >90% of lymphocytes formed!).
What type of immunity are T-Lymphocytes? B-Lymphocytes?
T-Lymphocytes, cell-mediated immunity (activation of phagocytes, no antibodies)
B-Lymphocytes, humoral immunity (plasma cells secrete antibodies)
T or F? The mechanism of activation of B-lymphocytes involves the specific binding of the antigen to surface-expressed molecules called Surface Receptor Proteins.
False, B-cells has immunoglobulins
T-cells has surface receptor proteins (aka T-cell markers)
T or F? Macrophages and B-cells internalizes antigens after specific recognition by surface-expressed immunoglobulins.
False, only B-cells, macrophages phagocytizes antigens
What are the similarities and differences between nonspecific inflammation macrophages and specific immune response macrophages?
Similarities: Phagocytize particulate matter and microbes.
Secrete antimicrobial chemicals and cytokines such as IL-1 and TNF
Differences: More efficient because antibodies act as opsonins and because the cells are transformed into activated macrophages (“super macrophages”) by IL-2
T-lymphocytes only respond when the antigen is bound to special surface molecules called ___ ____ _____, on the external surfaces of APC’s
Major Histocompatibility Complexes, (MHC’s)
What are the 3 major types of APC (antigen presenting cells)?
Macrophages, B-lymphocytes, and Dendritic cells
Major Histocompatibility Complexes, (MHC’s) has 2 general classes, MHC1 and MHC2. Which cells do each present to?
MHC1’s present to Cytotoxic T-lymphocytes while MHC2’s present to T-Helper cells
Helper T-cells secrete _______ after presentation/activation which enhances the activation of processed B-lymphocytes
lymphokines (without this “enhancement” the amount of antibodies secreted by B-lymphocytes would be small and probably insufficient so these cells are crucial in producing an effective response)
T or F? Fully activated B-lymphocytes enlarge and become Lymphoblasts → Plasmoblasts → Plasma cells.
True
Which transitional phase of a B-cell does the ER proliferate greatly to increase protein synthesis?
Plasmoblasts
Where do plasma cells originate and what is its’ function?
Some fully activated B-lymphocytes eventually becomes plasma cells. Plasma cells produce lots of specific antibodies.
T or F? Some of the activated B-lymphocytes do not become Plasma cells but are retained together with a small number of original processed/programmed B-lymphocytes to become memory cells.
True, these again circulate throughout the body to the various lymphoid tissues where they remain dormant until activated again by the same specific antigen.
T or F? “Memory cells”, on subsequent exposure to the same antigen can produce a far more rapid and effective response: this is primary response.
False, this is secondary response.
What types of cytokines do macrophages produce during specific immune response?
Interleukin-1 (IL-1), Tumor Necrosis Factor (TNF), stimulates proliferation, maturation, and activation of Th, B, and NK lymphocytes: causes inflammation, fever
Antibodies are gamma globulins called _____________.
Immunoglobulins (Ig) [20% of all plasma proteins)
T or F? Antigens are composed of combinations of “light” and “heavy” polypeptide chains, all are composed of 2 of each, creating 2 binding sites.
False, not all are composed of 2 binding sites (bivalent [IgG]), they could have up to 10 (decavalent[IgM])
What “portion” of the heavy-light pairing determines the antigenic specificity?
“Variable portion., The “constant portion” determines other general properties of the antibody such as opsonization, interactions with the Complement system, etc
The affinity of an antibody for its specific antigen is described similarly to these other interactions (formula)
Affinity (Ka) = [concentration of bound antibody-antigen complex]/[conc. free antibody] x [conc. free antigen]
What are the 5 general classes of antibodies and which one is the most significant?
IgM, IgG, IgA, IgD and IgE. Most significant is IgG which is bivalent and comprises ~ 75% of all antibodies in the body.
IgE and IgM are found in much lower concentrations, why are they important?
IgE is involved in allergic reactions, while IgM is produced during the primary response and is particularly effective due to possessing 10 binding sites.
What are the 2 general mechanisms that antibodies use to destroy/inactivate the antigenic material they specifically bind to?
Either directly or via the Complement system
What are the types of direct interactions of antibodies?
Agglutination -bound and clump together
Precipitation-linked molecules too large to become soluble
Neutralization-binding antibodies cover/inactivate toxic sites of invader
Lysis-rupture membranes, however, require “amplifying” effect of the Compliment system.
There are 11 out of ~20 proteins that are significant in the “complement system”, which ones are they?
C1 → C9 + “B” and “D
How are C1 activated?
Specific antibody-antigen interactions which “reveals” a special site on the constant portion of the antibody that now binds Complement factor C1 and activates it.
Which activated Complement factor fragments forms the so-called Membrane Attack Complex (MAC or Lytic Complex)?
C5b + C6→C9
Activated Complement factor fragment ____ causes chemotaxis of both neutrophils and macrophages, (along with increase phagocytosis), towards the site of the antibody-antigen reactions.
C5a
Which activated Complement factor fragments activate Mast cells and basophils towards the site of antibody-antigen reactions stimulating the Complement cascade
C3a, C4a, C5a
T or F? Activated T-lymphocytes circulate throughout the body first via the blood and then via the lymph after entering tissues and then back to the blood: they repeat this journey many times over months or even years.
True
T or F? Only B-lymphocytes can form “memory” cells.
False, T-lymphocytes can as well
What are the 4 major types of T-lymphocytes?
Helper,” “Cytotoxic,” “Suppressor,” and the “Natural Killer” cells, (NK).
Which T-cells are responsible for regulating virtually all immune functions?
Helpter T-cells (most abundant, ~75%)
What types of lymphokines are released by the helper t-cells?
Interleukins 2 → 6, Granulocyte-monocyte Colony-stimulating factor and Interferon-gamma.
Acquired Immunodeficiency Syndrome, (AIDS), the virus destroys principally the ______.
Helper cells
What is significantly reduced especially in the absence of Interleukins 4, 5 and 6?
Antibody production
What are specific functions of Help t-cells?
Include effective activation of both Suppressor and Cytotoxic T-lymphocytes (via IL-2) and the stimulation of B-lymphocyte growth and differentiation into antibody-secreting Plasma cells
T or F? Lymphokines also help prevent migration of macrophages previously attracted by chemotaxis away from the invaded tissue and increase their effectiveness at phagocytosis.
True
Which interleukin produces a +feedback loop by stimulating Helper cells themselves to increase immune response overall.
Interleukin 2
Which cells can ↓function/effectiveness of both Cytotoxic and Helper T-lymphocytes?
Suppressor cells, they can help suppress autoimmune responses. (Together with Helper cells they are classified as regulatory T-cells)
How do cytotoxic t-cells kill invading microorganisms?
- They kill their specific targets by punching a hole through their membranes, (= channel), via proteins called Perforins
- They also release cytotoxic substances directly into their targets: this process can be repeated many times by these cells.
What are 3 ways self antigens can become tumor antigens?
- Mutation
- Overexpression
- Post-translated modification
What are the main targets of Natural Killer (NK) cells?
virus-infected and cancerous cells
T or F? Natural Killer (NK) cells utilizes perforin to kill cells.
False, they use cell-killing chemicals
NK’s are not antigen specific, why are they included in both the acquired/adaptive immunity and innate immunity?
Because their participation is enhanced either by certain antibodies or cytokines secreted by Helper T-lymphocytes which are triggered by specific antigens.
What are increased/decreased during a general response to infection?
↑WBC production ↑plasma fatty acids, (fuel) ↑amino acids, (repair) ↑acute phase proteins, (inflammation and tissue repair) ↑cortisol, (the "stress" hormone) ↑ fever decrease food intake and appetite.
During infection, what is the purpose of a fever?
Appears to enhance immune responses.
What is Tolerance?
Failure to mount an immune response to self-antigens. (loss of tolerance will trigger autoimmune response)
How does immunization work?
It eliminates the primary response delay and goes directly to secondary response.
What ways are used to create immunization?
Injecting dead organisms no long pathogenic but still have antigenic properties
Chemically-neutralized toxins which still have antigenic properties.
Using a live attenuated (weakened) organism that has been sufficiently mutated, no longer pathogenic but has antigenic properties.
What is passive immunization/immunity?
injection of specific antibodies produced from another source or specifically activated T-lymphocytes or both.
What are some ways people express servere allergic response or some other form of hypersensitivity?
- Caused by T-cells due to repeated exposures.
2. An allergic tendency (inherited) characterized by excessive IgE antibody levels in the blood.
What causes an alleric response?
When an “allergen,” (a specific antigen that reacts with IgE antibodies), enters the body, it induces an “allergen-reagin” reaction which causes the allergic response.
IgE antibodies often attach themselves to _________ and _______ causing them to rupture.
Mast cells ; basophils
Allergic responses rupture certain cells that release various substances. What are they?
histamine, proteases, Slow-reacting Substance of Anaphylaxis, Eosinophil Chemotactic Substance, Neutrophil Chemotactic Substance, heparin and platelet activating factors. (These cause inflammation)
What is anaphylaxis?
An extreme response triggered in tissues immediately surrounding small blood vessels due to Mast cells and eosinophils that rapidly spreads throughout the circulation and associated tissues. (need to use epi-pen [adrenalin])
T or F? Slow-reacting Substance of Anaphylaxis can cause muscle spasms in the smooth muscle in the walls of the bronchioles eliciting an asthma-like attack which has the potential to kill by suffocation.
True
What is urticaria?
Hives triggered by allergens entering certain skin areas and the subsequent release of histamine causing swelling and a red “flare”.
What is hay fever?
Allergen-reagin reaction occurs in the nasal passages with released histamine, sneezing as the body tries to eject the causative agent.
What is asthma?
Allergen-reagin reaction occurring in the bronchioles but is less severe than anaphylaxis.
Which leukocytes are involved in the innate immune response?
All granulocytes and mono/macrophages. NK cells as well.
Which leukocyte is found in the greatest number in the blood stream?
Neutrophils
What type of messenger stimulates leukocyte production in the bone marrow?
Colony stimulating factors (GM-CSF, G-CSF, or M-CSF)
What is opsonization?
Enhanced phagocytosis
Does binding complement factor C3b activate the complement cascade?
No
*T or F? The “alternate” Complement pathway facilitates the perforation of bacterial cell membranes by Perforins?
False. (ALL complement pathways lead to the MAC; cytotoxic cells utilize perforins)
*The most “important” cell in the acquired/adaptive response is the _______?
the Helper of course! (but don’t forget the regulatory suppressors)
*MHC II proteins are expressed by?
APCs
*MHC II protein receptors are found on?
Helper T-cell
*MHC proteins/receptors are not required to directly activate?
NK cells
Which leukocytes are involved in the innate immune response?
all granulocytes and mono/macrophages.
Which leukocyte is found in the greatest number in the blood stream?
neutrophils.
What type of messenger stimulates leukocyte production in the bone marrow?
colony stimulating factors.
What is opsonization?
enhanced phagocytosis.
Does binding complement factor C3b activate the complement cascade?
no.
Macrophages can release?
lipases (for thickened bacterial membranes), bactericidal enzymes and oxidizing agents (ROS’s).
What ligand/s are involved in margination and diapedesis?
: Integrin, selectin and chemokine.
A chemokine is what kind of messenger?
a chemotactic agent (it’s the balloons!).
High or low affinity- what????
without the chemokine there is no change to high-affinity for the integrin receptor and no escape from the river!
Which group of proteins generally inhibit viral replication?
interferons.
Where are lymphocytes processed to avoid self-recognition/autoimmune responses?
ALL produced in the bone marrow (BM); T-cells move to the Thymus for processing whereas B-cells remain in the BM after birth BUT are processed in the liver while still a fetus
In Leukemia the more undifferentiated the leukocytes the more function they have? (T/F)
F
Leukopenia is often caused by exposure to gamma or X-rays?
T/F
T.
Repeating/reoccurring antigenic molecular groups called epitopes are observed only in proteins? (T/F)
F
After processing lymphocytes are primarily found in?
lymphoid tissue such as lymph nodes.
