Immunology Chapter 1

What are the two branches of the immune system?

adaptive and inate

What is the quickest immune system to response to an infection?

inate immune system

What is a downfall to the inate immune system?

it is not specific to any type of infection when attacking it which will not be enough to contain it

What are the two types of cells that are under the adaptive immune response?

B cells and T cells

What is humural mediated immunity?

b cells

What is cell mediated immunity?

t cells

Where does be cells offer immunity?

fluids of the body

What secrets b cells?

antibodies

Where do T cells work?

infection inside the cells

antibodies

proteins that are able to bind to bacteria and viruses

How do antibodies work in controlling an infection?

Block bacteria from growing colonies or the proteins bind to the viruses from infecting cells

pathogen

any disease casusing agent

immunology

the study of physicological mechanisms that are used to defend the body from invasion by foreign or infectious agents

Where does humans get the inate immune system?

through parents

Where do we recieve the adaptive immune system?

through expereiences

Why is it important that the adaptive immune system is flexible through its defenses?

so we can keep up with the everchanging microbes

What type of immune system is older?

inate

When did the adaptive immune system show up?

in vertebrates

What type of immune system deals with the destruction of pathogens?

inate immune system

Opsonization

the process of antibodies binding a pathogen to contain the infection

What are the type types of T cells?

CD4+ and CD8+

What does CD8+ stand for?

cytotoxic T cells

What is the purpose of Cytotoxic T (CD8+) cells?

they kill other infectious cells and sometimes cancer cells

What color are gram positvies?

purple

what color is gram negatives?

pink

What is the difference between gram positives and gram negatives?

gram positives have a thicker cell wall, gram negatives have two phosolipid bilayer which has embedded lipopolysaccharides

What happens when attacking gram negatives?

when antibodies attach to LPS they burst and release endotoxin which can lead to shock due to high levels of toxins

What is inbdedded in the gram positive plama membrane?

teichoic acids and lipoteichoic acids

lipoteichoic acids (LTA)

surface antigens that are linked to the cell membrane in gram positives

techoic acids (TA)

give cell wall a negative charge that are plasma membrane

What are the different types of gram positives?

Bacillus, Staphylococcus areus, Streptococcus and Mycobacterium

What are the different types of gram negatives?

E. coli, Pseudomonas, Salmonella, Shigella

What are NK cells?

type of white blood cell that are part of the inate immune system

What does NK cells stand for?

Natural Killer cells

Why are NK cells important?

They kill virus-infected cells and cancer cells without needing prior exposure.

How do NK cells kill virus infected cells?

They destroy target cells by releasing perforin and delivering granzymes leading to cell destruction

Perforin

pore forming protein in the immune system that allows content to be delivered in a cell

Granzymes

death enducsing enzym that leads to cell apoptosis

How do NK cells communicate with other immune cells in the body?

They also release cytokines that help activate other immune cells.

Cytokines

protein messenger that acts as the body's cellular communicators to signal, recruit, and regulate immune cells against infections and inflammation

What is the purpose of NK cells?

rapid-response immune soldiers that patrol for unhealthy cells and eliminate them before infections or tumors spread.

What does ILC stand for?

Innate Lymphoid Cells

What are ILCs?

a group of immune cells that are part of the innate immune system. They act quickly, especially at barrier surfaces like the gut, lungs, and skin.

What makes ILC cells different from T and B cells?

they do not have a antigen specific receptor

What does ILC respond rapidly to?

They respond rapidly to cytokines and tissue signals, not specific pathogens.

What is the prupose of ILC cells?

fast-acting immune cells that help protect body surfaces, control inflammation, and maintain tissue health before the adaptive immune system kicks in.

What ILC is NK cells part of?

ILC1

Why is ILC1 important?

Important for defense against viruses and intracellular pathogens

What does PRR stand for?

Pattern Recognition Receptors

What is PRRs?

receptors of the innate immune system that detect common molecular patterns found on pathogens or signals from damaged cells.

What does PRRs regonize?

PAMPs and DAMPs

Wherer are PRRs found?

immune cells like macrophages, dendritic cells, neutrophils, and epithelial cells.

What does the activation of PRR cause?

inflammation, cytokine release, and helps activate the adaptive immune system.

What is the purpose of PRR?

immune system’s early warning sensors that recognize invaders or cell damage and start the immune response quickly.

What does PAMPs stand for?

Pathogen-Associated Molecular Patterns

What are PAMPs?

molecular structures found on pathogens that are recognized by the innate immune system.

Where are PAMPs found?

on unhealthy host cells, which help tell the immune system from “ self” to “not self”

What will happen after the recognition of PAMPs?

inflammation and immune activation.

What are common examples of PAMPs?

LPS found in gram negative bacteria, or peptidoglycan which is found in bacteria walls

What is the purpose of PAMPs?

“red flags” on microbes that alert the immune system that a pathogen is present, allowing a rapid immune response

Epitope

the specific part of an antigen that is recognized and bound by the immune system.

What is another word for epitope?

antigenic determinant

Does a single antign have one epitope?

no, an antigen can have mutliple epitopes

What are the difference between the epitopes between T and B cells?

B-cell epitopes are often on the surface of proteins or carbohydrates and can be linear or conformational while T-cell epitopes are short fragments that are presented by MHC molecules to T cells.

Where does TCR, BCR, and antibodies bind to?

epitopes

What is an explanation of epitopes in simple terms?

an epitope is the precise piece of a pathogen or antigen that the immune system targets. If an antigen is a lock, the epitope is the specific keyhole that immune cells recognize.

What does MHC stand for?

Major Histocompatibility Complex

What is MHC?

a group of cell-surface proteins that help the immune system recognize which cells belong to the body and which do not.

Why are MHC proteins important?

they are essential for T cell activation

Does everybody have the same variant of MHC?

no, everyone has different variants of MHC proteins which is important in organ transplants

How does MHC help in T cell activation?

The MHC protein needs to show the T cell the epitope on the cell surface for the T cell to scan with the TCR and then if the TCR matches the epitope and MHC type, the T cell will recognize it as foreign which leads to T cell activation

Where is MHC Class I found?

Found on almost all nucleated cells.

Where does MHC Class I present antigens from?

inside the cell

Where does MHC Class II present antigens from?

outside the cell

What recognizes MHC Class I?

CD8+ cytotoxic T cells

What is the purpose of MHC Class 1?

Signals when a cell is infected or abnormal, says “ This cell is infected”

What is the purpose of MHC Class II?

Helps coordinate immune responses, says “there is a cell infected nearby”

What recognizes MHC Class II?

CD4+ helper cells

Where are MHC Class I proteins found?

antigen-presenting cells (dendritic cells, macrophages, B cells)

In simple terms what does MHC do?

display cases on cells that show pieces of proteins so the immune system can decide whether the cell is healthy or dangerous.

What are antige presenting cells?

immune cells that capture antigens, process them, and present antigen fragments (epitopes) on MHC class II molecules to activate T cells.

What does BCR stand for?

B Cell Receptor

What does TCR stand for?

T Cell Receptor

Do all B cells have multiple BCRs at once?

no, each B cell has a unique BCR, giving it antigen specificty

What is a BCR?

the sensor on a B cell that recognizes a specific antigen and starts the antibody-mediated immune response.

What is TCR?

lock-and-key receptor that lets T cells recognize infected or abnormal cells by reading peptide “labels” displayed on MHC molecules.

free antigen

an antigen that is not attached to an MHC molecule or presented by a cell, and is instead floating freely in the body or on the surface of a pathogen.

Who can recognize free entigens?

antibodies and b cell receptors

Why cant TCR not attach to a free antigen?

they require antigen to be processed and presented on MHC molecules.

BCR can attach to antigens because?

B cells can bind free antigens because their receptors are antibodies that are built to grab antigens directly, without help from other cells like MHC presentation or antigen processing

What are antibody titers?

measure the amount (concentration) of specific antibodies present in a person’s blood.

What is the usage of antibody titers?

uses to see response to vaccination, immunty, infection

The higher the antibody titer then…

the more antibodies against that antigen

What is C3b?

key protein fragment of the complement system that plays a major role in marking pathogens for destruction.

What is C3b in simple terms?

molecular “sticky note” that labels pathogens so immune cells can quickly find and destroy them.

What is the purpose of C3b?

Tags bacteria and viruses for phagocytosis. Enhances immune clearance. Helps drive further complement activation

What is complement activation?

the process by which a group of blood proteins called the complement system is turned on to help the immune system destroy pathogens and clear damaged cells.

Once activated what does complement acitvation do?

Tag pathogens for phagocytosis (opsonization). Trigger inflammation. Directly kill microbes by punching holes in their membranes

opsonization

the process by which pathogens are “tagged” to make them easier for immune cells to recognize and ingest.

Why is opsonization important?

Many pathogens resist direct phagocytosis. Opsonization acts like a “handle” that immune cells can grab onto. Increases speed and efficiency of pathogen clearance.