Lesson 12: Immune System Part I

Which of the following are examples of Professional (MHC II) Antigen Presenting Cells (APCs)? I. Macrophages II. Basophils III. T Cells (A) I Only (B) II Only (C) I and II Only (D) I and III Only

(A) I Only Examples of Antigen Presenting Cells (APCs) include Macrophages, Dendtritic Cells and B Cells.

*CRB* There are also Gut-Associated Lymphoid Tissues (GALT) involved in the immune response. Which of the following is NOT one of these? (A) Liver (B) Appendix (C) Adenoids (D) Tonsils

(A) Liver The GALTs include the Tonsils, Adenoids, Peyer's Patches in the small intestine, and the Appendix's lymphoid aggregates.

*CRB* What is the role of bone marrow in the immune system then? (A) Produce Immune Cells (B) Mature Immune Cells aggregate here (C) Mature Immune Cells come here to detoxify (D) There is no role for Bone Marrow in the Immune System.

(A) Produce Immune Cells The Bone Marrow produces various Immune Cells.

*CRB* Which of the following are antibacterial enzymes found in the skin? (A) Sweat (B) Defensins (C) Integrins (D) Langerhans

(B) Defensins Defensins are antibacterial enzymes found in the skin. Sweat is not an enzyme, but it does have microbial properties!

*CRB* Which of the following are areas that would have Lysozyme, a nonspecific antibacterial enzyme, secreted? I. Around Eyes II. In Oral Cavity III. In the Ears (A) I only (B) I and II only (C) II and III only (D) I, II and III

(B) I and II only Lysozymes are secreted from areas that have mucous membranes, like around the eyes (in tears) and the oral cavity (in saliva).

*CRB* Which of the following are ways that the Complement System can be Activated? I. The Classical pathway requires that antibodies have bound to a pathogen. II. The Alternative Pathway does not require antibodies. III. The Operant Pathway uses direct activation by activated B cells. (A) III only (B) I and II only (C) I and III only (D) II and III only

(B) I and II only The Complement system can be activated in 2 ways: I. The Classical pathway requires that antibodies have bound to a pathogen. II. The Alternative Pathway does not require antibodies.

B Cells have receptors presented on their membranes that recognize the proteins of invaders. We might think of these receptors as: (A) Membrane-bound Antigens (B) Membrane-bound Antibodies (C) Membrane-bound MHC I (D) Membrane-bound MHC II

(B) Membrane-bound Antibodies Each B-lymphocytes have membrane-bound antibodies (aka Immunoglobulins) on their surfaces. Antigens refer to the proteins that are recognized by antibodies.

*CRB* At which of the following places are B-cells activated? (Hint it is also a location of blood storage) (A) Bone Marrow (B) Spleen (C) Capillaries (D) Lymphatic Vessels

(B) Spleen The Spleen both is a location of blood storage and activates these B-cells! (Sorry about the tricky hint, but now you know two things about the spleen!)

Which of the following act as the first line of defense in keeping pathogens out of our body? I. skin II. mucous membrane III. nails (A) III only (B) III and I only (C) I and II only (D) I, II, and III

(C) I and II only Skin and mucous membrane act as the first line of defense in keeping pathogens out of our body.

*CRB* Which of the following is another term for an activated B-cell, which could produce antibodies? (A) Killer Cell (B) Proliferative B Cell (C) Plasma Cell (D) Memory B Cell

(C) Plasma Cell A Plasma Cell is an Activated B-Cell that can produce antibodies.

*CRB* In which of the following places to T-cells mature? (A) Bone Marrow (B) Thyroid (C) Thymus (D) Thanos

(C) Thymus The Thymus, a gland near the pericardium, is where T-cells mature.

Immediately following a break in the skin, phagocytes engulf bacteria within the wound. This is an example of an _________ immune response which is __________ against a pathogen. A) adaptive, specific B) innate, specific C) innate, non-specific D) adaptive, non-specific

(C) innate, non-specific. Adaptive immunity mounts a response against a specific antigen, where as innate immunity mounts a general response against any antigen. SO they work by " ohh this is a virus, idc what type, i'm just gonna get rid of it"

Which of the following is an example of a pathogen? I. Virus II. Parasite III. Fungus (A) I Only (B) II Only (C) II and III Only (D) I, II, and III

(D) I, II, and III Pathogens are any disease-causing agent and include viruses, bacteria, parasites, fungus, certain proteins, etc.

Which of the following are different types of phagocytes in the body? I. Neutrophils II. Macrophages III. Dendritic Cells (A) III only (B) III and I only (C) I and II only (D) I, II, and III

(D) I, II, and III. Neutrophils, Macrophages and Dendritic Cells are all different types of phagocytes found in the body.

*CRB* Fill in the blanks: The MHC-II class has antigens that originated _____________ of the cell, so it is often called the ________________ Pathway. (A) Inside, Endogenous (B) Inside, Exogenous (C) Outside, Endogenous (D) Outside, Exogenous

(D) Outside, Exogenous The MHC-II class has antigens that originated Outside of the cell, so it is often called the Exogenous Pathway.

*CRB* True or false? MHC class I molecules are on all nucleated cells in the body and have antigens produced inside of the cells to identify them as belonging to the organism, and this MHC-1 Pathway is called the Endogenous Pathway.

True. MHC class I molecules are on all nucleated cells in the body and have antigens produced inside of the cells to identify them as belonging to the organism, and this MHC-1 Pathway is called the Endogenous Pathway. Note that this card specified "nucleated" cells. Non-nucleated cells can vary; red blood cells do not have MHC Class 1 proteins, but platelets do have MHC Class 1 proteins.

*CRB* True or false? The Lymph Nodes are a place where immune cells can communicate and coordinate attacks, including activating B-cells.

True. The Lymph Nodes are a place where immune cells can communicate and coordinate attacks, including activating B-cells.

*CRB* True or false? The innate part of the immune system acts closer to the entry points for pathogens than the adaptive part of the immune system.

True. The innate part of the immune system acts closer to the entry points for pathogens than the adaptive part of the immune system.

True or false? The main actors of the specific immune system are lymphocytes.

True. The main actors of the specific immune system are lymphocytes such as B and T Cells.

*CRB* Fill in the blanks: After already being exposed to the flu two months ago, a nurse is exposed a second time. This would likely trigger the _____________ immune response which is ________ against a pathogen. A) adaptive, specific B) innate, specific C) innate, non-specific D) adaptive, non-specific

A) adaptive, specific After already being exposed to the flu two months ago, a nurse is exposed a second time. This would likely trigger the Adaptive immune response which is Specific against a pathogen.

Describe how a non specific response by a phagocyte can eventually lead to a possible specific response?

After phagocyte consumes and kills the pathogen that it engulfed, the phagocyte will take small pieces of protein from the pathogen and attach it to the major histocompatability complex type II, and then phagocyte presents it on its membrane. Antigen presentation. This recruits other specific immune system molecules to carry out a specific response if it recognizes part of the destroyed pathogen to be something it has a response to.

What is the primary difference between the role of B Cells vs. T Cells?

B Cells produce antibodies. T Cells recognize and destroy invaders and infected cells.

There are two major types of T Cells: Helper T Cells (Th) and Cytotoxic T Cells (Tc). What is the difference between these two?

Cytotoxic T Cells will recognize cells that are infiltrated by an invader and destroy those infected cells. Helper T Cells will recognize cells that are presenting an antigen via MHC II. Upon binding they will divide into Memory and Effector Th Cells.

What is the role of Effector Th Cells vs. Memory Th Cells?

Effector Th Cells will release Cytokines, which act as the alarm system causing inflammation and activating other immune cells. Memory Th Cells are basically copies of the original Th Cell. Their purpose is to recognize future invaders of the same type, hence the name "memory".

What is the name of the part of the bacteria that antibodies bind to?

Epitope

True or false? Dendritic cells are phagocytes that are part of the nervous system.

False. Dendritic cells have nothing to do with the nervous system. They tend to be the best actuators of the specific immune system.

True or false? The humoral response of the B-lymphocytes comes into play if the cell has been colonized by a virus or bacteria

False. Humoral response comes into the picture if the bacterial/virus cells are floating around in the humoral fluid and haven't colonized a cell yet.

True or false: only one epitope is possible to be presented from a particular virus strain.

False. More than one epitope could be presented from the same virus strain. An example of this would be a dendritic cell presenting a part from inside the virus and a B cell may present a part from the outside of the virus.

True or false? Macrophages are the fast and abundant phagocytes.

False. Neutrophils are the fast and abundant type of phagocytes. Macrophages are the the most versatile but not as abundant as neutrophils.

True or False? Stomach acid acts as a second line of defense in keeping pathogens out of our body.

False. Stomach acid, acts as a first line of defense in keeping pathogens out of our body.

*CRB* True or false? The Cell-Mediated Response is mediated by both B and T Cells.

False. The Cell-Mediated Response is mediated only by T-cells.

*CRB* There are many types of Macrophages that are found in only certain tissue types. Can you name the specific tissues where the following Macrophages can be found? I. Langerhans Cells II. Osteoclasts III. Microglia

I. Langerhans Cells - Skin II. Osteoclasts - Bone III. Microglia - Central Nervous System

What are examples of second lines of defense in our bodies?

Inflammatory response (bringing stuff to fight bacteria that entered) Phagocytes - actually part of inflammatory response

Which acts faster? Non-specific/Innate Immunity or Adaptive/Specific Immunity?

Innate Immunity acts faster as Adaptive Immunity requires time to recognize and prepare defenses against invaders. Think about how B and T Cells need to replicate and divide in order to prepare for a certain invader.

What is the difference between Non-specific/Innate Immunity and Adaptive/Specific Immunity? Give some examples of each.

Innate Immunity targets any and all invaders. It is non-specific. Examples of this are phagocytes and the inflammatory response. Adaptive Immunity targets specific invaders. Examples are how B and T cells work.

When a pathogen binds to a receptor on a B-Cell, the B-Cell will become activated and start to replicate forming both Memory B Cells and Effector B Cells. What is the difference between these two B Cell types?

Memory B Cells are basically copies of the original B Cell. Their purpose is to recognize future invaders of the same type hence the name "memory". Effector B Cells are Antibody producing "factories" with the sole purpose of producing tons of antibodies.

Antibodies have various mechanisms of action, including Opsonization, Neutralization, and Agglutination. Describe each of these three mechanisms.

Opsonization - tags pathogens for phagocytosis by other white blood cells. Neutralization - masks dangerous parts of the pathogen, making them no longer pathogenic. Agglutination - Multiple pathogens are bound up together, making them easier for digestion/phagocytosis.

Describe or draw what happens when a Phagocyte comes in contact with an invader such as a bacteria.

Phagocytosis will occur, resulting in the formation of a Phagosome, which is basically the bacteria surrounded by a membrane (bacteria in a vesicle). The Phagosome will then fuse with the Lysosome, digesting the bacteria.

Instead of just disposing of the disgested bacteria, what will the host cell do with fragments of the digested invader if it is a Professional Antigen Presenting Cell (APC)?

Professional Antigen Presenting Cell (APC) have Major Histocompatibility Complex II (MHC II) proteins that will bind to fragments of the digested bacteria and then present them on the external surface of the host cell. A similar mechanism dine with phagocytes can be done in B cells as well

Describe T Cell dependent B Cell Activation? Why is it important?

T Cell dependent B Cell Activation is a fail-safe mechanism to ensure that B Cells are actually recognizing an invader and not a self-antigen (an antigen from your own body). It means that B Cells will only become activated if their receptor binds to an antigen and a Th Cell binds to one of its MHC IIs.

*CRB* There are also antimicrobial molecules that can attack invading microorganisms. Would this be considered part of the Innate or Adaptive Immune System?

The Antimicrobials are not specific to any particular microorganism, so they are part of the Innate Immune System.

Adaptive Immunity includes both the Humoral Response as well as the Cell-mediated Response. Compare these two.

The Humoral Response is carried out by B Cells, entailing the production of antibodies. The Cell-mediated Response is carried out by T Cells, which act on cells that are infected by pathogens.

*CRB* Compare the Complement System and Interferons, which are two other parts of the nonspecific Immune Response.

The complement system is based off many proteins in the blood, and will punch holes in bacterial cell membranes in the blood. Interferons are proteins that prevent viral replication and dispersion, and will be produced by cells that have been already infected by viruses.

What is the role of the Fixed Portion of this membrane-bound Antibody? What about the Variable Portion?

The role of the Fixed (Constant) Portion is to attach to the membrane and give the antibody its structure. The role of the Variable Portion is to bind to a specific antigen.