Immune System BASICS

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Sebum

What do sebaceous glands secrete?

It is a physical barrier to pathogens, it is an oil

What does sebum do?

Epidermis, dermis, hypodermis

What are three layers of the skin?

Mucous membranes and sebaceous glands

What two glands does the skin have?

They trap pathogens that pass through the skin bc of a cut or opening and they secrete lysozyme

What do the mucous membranes do?

Antimicrobial proteins that non-specifically break down bacterial cell walls

What is lysozyme?

It keeps the skin at a pH from about 3-5 and pathogenic bacteria can’t survive that low pH level

How does Sebum keep pathogens from coming in?

Sebaceous glands, mucous membranes, cilia, and stomach acid

What are the physical barriers of the innate immune system?

Symbiotic bacteria, these are good bacteria that destroy pathogens

What is technically a physical barrier of the innate immune system but not?

Because the low pH kills off bacteria

Why is gastric/stomach acid a physical barrier?

With enough symbiotic bacteria it will be enough to beat out the bad bacteria because of their numbers. They Out-Compete them

What does symbiotic bacteria do?

If one of your physical barriers are penetrated

When does the Inflammatory response happen?

The Mast Cell

What sounds the alarm for the innate immune system to begin inflammation?

They are leukocytes or WBCs sitting in the tissues

What are Mast cells?

They release histamine, the injured cells also release this

What do Mast cells do when injuries occur?

Histamine dilates nearby capillaries, and makes capillary walls more permeable so that immune cells can get to the site of injury bc they can pass through the capillary walls

Histamine

It means you get an increased bloodflow

What do widened capillaries do?

Heat, Redness, Swelling, Pain, and Loss of Function

What are the 5 signs of inflammation?

Swelling, Loss of Function, Increased Heat, Pain, Redness

SLIPR

Basically another inflammatory response, your brain turns it on when it realizes that pathogens have entered the body . Increased body temperature hinders growth of pathogens, and kills temperature sensitive pathogens

Fever

The process of cells moving from capillaries to tissues. Happens after histamine is released from mast cells

Diapedesis

Process of moving to a location in response to a chemical signal

Chemotaxis

White Blood Cells

What kind of cell specifically uses Chemotaxis?

A type of immune cell that plays a role in activating the innate immune system (NO NUCLEUS)

Platelets

1. To regulate the regulation and maturation of macrophages, neutrophils, and dendritic cells
2. Act as immune systems first responder when foreign entities enter the bloodstream

What are the functions of the platelets?

NO they’re not white blood cells, yet they do play a vital role in the immune system

Are platelets white blood cells?

A CATEGORY of cells characterized by having specific granules in their cytoplasm

Granulocytes

Neutrophils, Basophils, Eosinophils, and Mast Cells

What are the cells that are Granulocytes?

Neutrophils>Lymphocytes>Monocytes/Macrophages>Eosinophils>Basophils (THESE ARE ALL TYPES OF LEUKOCYTES\[WBCs\])

Never Let Monkeys Eat Bananas (HIGHEST NUMBER OF THEM TO LOWEST NUMBER OF THEM IN OUR BODY)

You should think of them as infantry units because they are the most numerous in the body and go in one of the first on an inflammation site

What should you think of Neutrophils as?

They are phagocytes, eat (phagocytosis) and destroy pathogens, they ENGULF all kinds of pathogens

What are neutrophils?

You should think of them as artillery units because they acquire the target before killing it.

What should you think of lymphocytes as?

B Cells, T Cells, and Natural Killer Cells

What are the three kinds of lymphocytes?

Lymphocytes

What is the most common WBC found in lymph

B Cells and T Cells, they need to get activated before they start doing anything

Which lymphocytes are part of the adaptive immune system?

Part of innate immune response, attack virus infected cells or cancerous body cells

Natural Killer Cells

1. Perforin- pokes holes in pathogenic cell membranes> cell lysis
2. Granzymes- proteases that stimulate a target cell to undergo APOPTOSIS

What are the two weapons of Natural Killer Cells?

Programmed cell death, useful in Natural Killer Cells for getting rid of cancerous body cells

Apoptosis

They are called Monocytes because they are not matured yet

What are Monocytes/Macrophages called when they’re in the blood vessels and why?

They are called Macrophages when in infected tissues because they are matured

What are Monocytes/Macrophages called when they’re in infected tissues and why?

They are phagocytes which eat pathogens nonspecifically. They also later serve as antigen presenting cells to activate our adaptive immunity

What do Monocytes/Macrophages do?

It is like a unique I.D. tag for the pathogens that our immune system will be fighting, it is like a mission briefing for our backup troops a.k.a. our adaptive immune response.

What can you think of antigens as?

We can think of them as messengers w/ vital information for the victory of the battle (think of 1917)

What can we think of Macrophages as?

Their cytoplasms are filled with GRANULES which contain proteins that are released to kill pathogens. ESPECIALLY effective against parasites

Eosinophils

EEWWosinophils they only serve 1 purpose DISGUSTANG

What can you think of Eosinophils as?

Cooler Eosinophils because Jeff Bezos

What can you think of Basophils as?

They contain granules that can be released to nearby tissues.

Basophils

What percentage of leukocytes are Basophils?

They are cool cuz they have HISTAMINE- which dilates blood vessels and makes capillaries more permeable and they have HEPARIN- which prevents blood from clotting too quickly

What do the granules of Basophils do?

Mast Cells and Basophils

What two Granulocytes are very similar?

Basophils leave the bone marrow and circulate in the blood as matured cells. Mast cells leave the bone marrow and circulate in the blood as immature cells (they mature when they enter the tissue)

What is the difference between Mast Cells and Basophils

Fat Security Guards

What can we think of Dendritic Cells as?

They take a sip from their surroundings through Pinocytosis. Once the pathogen is detected the dendritic cell will eat the pathogen through phagocytosis. They are also antigen presenting cells which end up going to the lymph nodes and activate the adaptive immunity

What do Dendritic Cells do?

That they’re antigen producing cells and they have Toll Like Receptors.

What do Macrophages and Dendritic cells share in common

they recognize microbes and trigger phagocytosis and other elements after binding occurs in cells that have them

Toll Like Receptors

A molecule released by virus infected cells to send messages to non-virus infected cells to help them prepare for a viral attack. They also activate dendritic cells which in turn activates our adaptive immune response

Interferon

A system of blood plasma proteins that help immune cells fight pathogens more effectively and includes about 30 proteins

Complement System

Immune system is Batman and the complement system is his sidekick Robin

What can we think of the Complement System as?

When those 30 proteins are helping an immune cell it must go through a cascade series of activation to turn all of them on. They turn each other on through protease activity

How does the Complement system work?

Improves the eating ability of phagocytosing cells through Opsonization which binds a special protein called C3B to antigens > this basically marks them and tells those immune cells what to go after to make their job easier

What is the first effect of the Complement System?

It amplifies inflammatory response, Proteins bind to mast cells>stronger histamine release from Mast Cells

What is the second effect of the Complement System?

It lyses pathogen membranes through Membrane Attack Complex (MAC)

What is the third effect of the Complement System?

HOW MAC WORKS 1. MAC proteins group up on the pathogenic membrane 2. Salt and fluids enter the pathogen through the holes 3. Pathogen swells and then bursts

What is Membrane Attack Complex?

The innate immune system attacks any pathogen no matter what kind but the adaptive immune system attacks unique pathogens after putting an antigen on them

What is the difference between the innate and adaptive immune systems in terms of antigen binding?

A non-self cell which will activate our adaptive immune response when it senses that they are there

What is a cell that has an antigen bound to it called?

All cells with a nucleus have major histocompatibility complex (MHC) class 1 molecules on their cell surface

How does the immune system recognize its own cells?

It basically is another identification tag to show that the cells that have this work here. Every unique individual has their own unique MHC 1. It depends on their genetic makeup

Major Histocompatibility Complex

They have the same MHC 1 expression

What happens if identical twins are born in relation to Major Histocompatibility Complex?

Found in the center of most bones and has many blood vessels

Bone Marrow

A small organ that lies in the upper chest under the breastbone. It makes lymphocytes

Thymus

Fights invading germs in the blood, Controls the level of blood cells (RBC, WBC and Platelets)., and Filters the blood and removes any old or damaged RBCs

Spleen

small bean shaped structure throughout the body. They filter substances that travel through the lymphatic fluid, and they contain lymphocytes that help the body fight pathogens

Lymph nodes

The donor organ will have a different MHC 1 than the person who is receiving the organ. So it will be viewed as a non-self cell rather than a self cell. So our immune system will attack this foreign organ which can lead to organ failure or transplant rejection

What is the problem with MHC 1 and Organ transplant?

Immunosuppressants to lower/stop immune system’s response to foreign organs. But these people are now more susceptible to general infections.

What do patients need to take for a successful transplant to happen?

An autoimmune disease is when the immune system mistakenly attacks self cells

What is a autoimmune disease?

Bridge between the innate and adaptive immune responses

Antigen Presenting Cells (APCs)

Macrophages and dendritic cells are both APCs because they have MHC 1 Molecules AND MHC 2 molecules on their cell surface ( normal nucleic cells only have MHC 1) Memory B Cells are also APCs because they can present the antigens to themselves and start creating antibodies

What cells are APCs and why?

1. APCs phagocytose pathogen
2. Break off antigen from pathogen
3. APCS load that antigen onto their MHC molecule
4. Antigen is presented to adaptive immune cells

How do APC bridge the innate and adaptive response?

BOTH MHC 1 and MHC 2

What two molecules can antigens be presented on?

Section of the antigen that is actually recognized by the adaptive immune cells (B Cells and T Cells).

Epitope

Little puzzle pieces that go into the slots on the B Cells and T Cells

What should you think of Epitopes as?

Produced in the Bone Marrow

Where are lymphocytes created?

**B** cells stay and mature in **B**one marrow

**T** cells stay and mature in **T**hymus

Natural killer cells stay in bloodstream

Mnemonic to remember where the different lymphocytes live after being created in the Bone Marrow

To conduct antibody-mediated immunity (HUMORAL IMMUNITY) which means they are going to control the production and release of antibodies

What is the B cells job?

1. B Cell Receptors (BCR) bind to antigen’s epitope ( either free floating antigen or APC presented antigen)
2. B Cell becomes activated
3. B Cell divides and makes many copies of itself

How do B Cells get activated?

Each B Cell has a unique uniform BCR that only binds to *one* kind of antigen

How is each B Cell unique?

1 Specific Antigen *SELECTS* 1 Specific B Cell to clone itself. Since each B Cell has a unique BCR the antigen selects which BCR to bind to > decides which B Cell to activate

Clonal Selection Model

Immunoglobins

What is another word for Antibodies?

They are a type of B cell that is formed after cloning with an antigen. They release antibodies (Immunoglobins) BCRS and Immunoglobins are structurally identical

Plasma Cells

1. Tag the specific corresponding antigen for removal (phagocytosed)
2. Coat the antigen in antibodies to neutralize it
3. Activate the Complement System

What is the job of an antibody?

A BCR is attached to a B cell while an antibody is free flowing in blood and lymph

How do BCRS and Antibodies differ?

Y shaped, made of light chain and heavy chain. Linked through **disulfide bonds**

Structure of Antibodies

Because antibodies are proteins constant regions have a similar amino acid coding sequence within a specific class of antibodies (Makes up 75% of the antibody)

Constant region of Antibody

The hypervariable region can bind to different antigens. This happens because differences in amino acid sequences allow binding to specific antigens

Hypervariable region of Antibody

Fragment Crystallizable Regions (FC)

What is the tail of the antibody called?

Fragment Antigen Binding (FAB) the very top is a subregion of the fab called the variable or hypervariable region

What are the arms of the antibody called?

Glycoproteins (carbohydrate added to amino acid residues)

What are antibodies? (In relation to their molecular structure)

They occur in the FC molecules. Glycosylation influence interaction with effectors molecules which will help with things like opsonization and the complement system

Where do they Glycosylation sites occur in the antibody?

Where we add a carbohydrate to another molecule

Glycosylation

IgM>IgA>IgE>IgD>IgG

List all of the types of antibodies