BI203 Exam 3

Innate Immune

• Present from birth

• Immediate but NOT SPECIFIC

• BUYS TIME for specific second line of defense

Adaptive Immunity

• Develops ONLY after exposure to antigen

• TAKES TIME but HIGHLY specific to target

• End of prodromal phase, maintained long after

What are antigens?

Any foreign molecule - typically proteins - trigger antibody production

Which branch of the immune system responds first to an infection?

Innate Immune → within minutes to hours → non specific defense against invaders

Which branch of the immune system takes longer to respond, but is more specific?

Adaptive immunity → takes several days to weeks to fully mount a primary defense.

B Cells

• Remember specific pathogen antigens

• Rapidly produce customized antibodies

T Cells

• Coordinate immune attacks

• Directly infected cells upon re-exposure

First line of defense against bacteria:

-Skin: protective shield w/ keratin

-Lungs: Sneezing is designed to clear the organism from the respiratory tract

-Acidic pH of stomach = lethal to most bacteria

-Acidic pH of vagina = suppresses bacterial/fungal growth

-Lysozyme → in tears, degrade cell walls

Second line of defense against bacteria:

Innate Immunity

WBCs → neutrophils & macrophages

Third line of defense against bacteria:

Adaptive Immunity

Antibodies → produced by B cells

T Cells

Memory B & T cells

All immune cells develop in the:

Bone marrow

Neutrophils:

1st responders - phagocytes - SHORT lived - no antigen presentation

Macrophages:

Phagocytes - LONGER lived - can present antigen

Eosinophils:

Release toxic molecules onto the surfaces of worms.

Basophils:

Release histamine - inflammation - allergies

Dendritic Cells:

Phagocytes - usually associated w/ skin and other tissues, can present antigen

Mast Cells:

Like basophils, bound to tissues

Helper T cells:

Adaptive - help active B cells to make antibodies

Cytotoxic T cells:

Adaptive - kill virally infected cells.

B cells:

Make antibodies.

What do macrophages bridge:

The innate and adaptive immune system

What is WBC differential?

A blood test that measures the percentage and actual number of each type of WBC in your blood.

Elevated Neutrophils:

Bacterial infections

Elevated Lymphocytes:

Viral infections

Elevated Eosinophils:

Parasitic infections or allergic reactions.

Physical Barriers:

Skin, mucous membranes, cilia, flushing actions.

Chemical Barriers:

Stomach acid, lysozymes, antimicrobial peptides, acidic body secretions.

Why was David Philip Vetter immunocompromised?

He was born w/ X-linked Severe Combined Immunodeficiency.

X-Linked Severe Combined Immunodeficiency:

Disrupts the development of lymphocytes (responsible for adaptive immunity)

Why would bone marrow transplant be curative?

Replaces the defective machinery at the source → replaces stem cells, creates a new blueprint, restores immune system

When a B Cell is activated by its partner helper t-cells, what 2 cell types can the B cell become?

Plasma cells and memory B-cells

Plasma Cells:

Actively synthesize, package, and secrete antibodies to neutralize current pathogens

Memory Cells:

Store “memory” to provide long-term immunity and fast secondary responses

Antigen presentation:

Primary bridge that connects the rapid, non specific response of innate to the targeted, long-term memory of the adaptive

What cells are cytotoxic t cells best at killing?

Virus-infected host cells and cancerous cells

What are antibodies made of?

2 heavy chains and 2 light chains

Constant region of antibodies:

Identical

Variable region of antibodies:

Ends of the antibodies unique structure

IgG

Most common, main antibody, only antibody that can be transmitted across placenta

IgM

2nd most common, main job = first antibody made against infection (pathogen)

IgA

3rd most common, found in bodily fluids, allows transfer of antibodies to babies through breast milk

IgE

Allergic responses, originally to protect from parasites

IgD

Antigen receptor on surface of B-lymphocyte to help activate B cells → trigger immune response.

If a patient has high levels of IgM would they have been recently exposed to a particular antigen or would IgM appear much longer after the initial exposure to the particular pathogen?

-Typically indicates a recent or initial exposure to an antigen

-IgM antibodies start appearing in the blood w/in 5 to 10 days

Which antibody isotype is secreted in bodily fluids like tears, intestinal fluid, breast milk, etc?

IgA

Which antibody isotype can cross the placenta?

IgG

What is meant by isotype switching?

Allows a B cell to change the type of antibody it produces, while keeping its antigen specificity the same.

What do Dermatophytes (fungi) love?

Human skin

What causes the majority of infections for fungal infections of the skin?

Epidermophyton, Trichophyton, and Microsporum

Signs and Symptoms of Impetigo + major causes:

honey colored crusted lesions on the mouth and nose → staph or strep

What is necrotizing fascitis?

Rare, fast spreading, and life threatening bacterial infection that destroys the fascia and soft tissue underneath

Why might hyperbaric oxygen help treat necrotizing fasciitis?

Strep lacks catalase enzymes. Can’t detox reactive oxygen.

What is Cellulitis?

Spreading REDNESS in dermal skin layers infection

What tissues are involved in cellulitis?

Only upper layers of skin, BUT has potential to go deeper if left untreated

What is Lymphangitis?

Infection of the lymph vessels = dangerous

Why might lymphangitis indicate sepsis?

Bacteria in lymph vessels/fluid can easily move into the blood stream.

How would KOH prep of skin or hair scrapings help diagnose fungal infections?

Dissolves human skin or hair cells while leaving tougher walls of fungi intact, which can be seen under a light microscope

Why is fever not typically seen with dermatophyte fungal skin infections?

Just localized to outer layers of skin.

Why is it bad when the skin is damaged due to a burn?

Pathogens have a direct route to infiltrate the body and cause disease.

What does P. aeruginosa look like on blood agar/how to ID:

Metal sheen on blood agar, green on NA. Smells grapey.

What does dry gangrene affect?

Fingers and toes, seen in severe frostbite cases and in ppl w/ diabetes or certain autoimmune diseases.

What does wet gangrene affect?

Internal or external part of body. Its necrosis due to an infection.

How do Clostridium perfringens kill tissues and void the host immune system?

It makes lots of them, good at killing tissues w/ toxins

What is the major cause of Keratitis and keratoconjunctivitis in the US?

Herpes Simplex 1

Antiviral medications that treat herpes keratitis:

Acyclovir & Trifluridine

Why are newborns given antibiotic eye drops?

Mom is asymptomatic with STDs when she gives birth and the STD may have caused a problem w/ the newborns eyes.

What two types of STDs may be an issue for babies?

Gonorrhea & Chlamydia

What is Trachoma?

Contagious, chronic eye infection and the world’s leading infectious cause of preventable blindness

What causes tachoma?

Chlamydia trachomatis

Clostridium perfringens

Gram +, Rod, spore former

What does Clostridium perfringens only grow on and why?

Only grows on dead tissue because it is a true saprophyte

What bacteria only infects traumatic wounds?

C. perfringens

Virulence factors for different strains of S. pyogenes:

Massive amounts of cytokines released can produce high levels of inflammation & lead to shock.

Conjunctivitis:

Inflam. of clear membrane that covers the white part of the eye & inner eyelids (pink eye)

Keratitis:

Inflam. of the transparent dome over the pupil & iris