12 immunity

Innate (nonspecific) defense system

1st and 2nd lines of defense

1st line of defense

skin and mucus membranes

2nd line of defense

phagocytes, fever, complement, interferon, NK cells, inflammation

Adaptive (specific) defense system 

3rd line of defense 

3rd line of defense

-attacks particular foreign substance

-longer

-T and B lymphocytes

Chemical barriers

Acid and enzymes

Ciliary escalator system 

Mucus coated hairs trap particles 

Cilia bring debris rich mucus toward mouth

Physical barriers breached by cuts

Types of phagocytes

Neutrophils

Macrophages 

Dendritic cells 

Neutrophils

Most abundant

1st there but die 

Macrophages

From monocytes

Chief phagocytic cells 

Dendritic cells

In skin and mucus membranes

Natural killer cells

Blood and lymph

Pore creation for chemicals (apoptosis) to enter 

Secrete cytokines 

Cardinal signs of inflammation

redness (rubor)

heat (calor)

swelling (tumor)

pain (dolor)

sometimes impairment of movement

Inflammation

immunovascular response to tissue injury

Benefits of inflammation

Prevent spread

Dispose of cell debris

Alert adaptive immune system 

Set stage for repair 

Stages of inflammation

Inflammatory chemical release

Vasodilation and increased vascular permeability 

Phagocyte mobilization 

Inflammatory chemical release

Histamine, bradykinin, prostaglandins cause vasodilation

Vasodilation and increased vascular permeability

causes swelling, redness, heat, and pain

RBC, WBC, platelets to injured area 

Phagocyte mobilization

Neutrophils via chemotaxis (movement of immune cells to area)

Antimicrobial proteins

attack directly

hinder ability to reproduce 

Types of antimicrobial proteins

interferon 

complement 

Interferons

Cells with virus can secrete these to warn other cells

complement

cascade of proteins for destruction

Complement pathways

classical-adaptive (antibody activated)

alternative-innate (bind directly)

Complement cell lysis

MAC inserts into cell membrane

influx of water and lysis 

Leukocytes and macrophages secrete what when exposed to foreign substances 

pyrogens 

pyrogens

raise body temperature

benefits of fever

liver and spleen isolate iron and zinc

Increase metabolic rate (increase repair)

Adult temp leading to seizure

105

infant low grade fever

98.6-100.4

infant fever to seek care

100.4-103

Innate vs adaptive 

innate-birth

adaptive-after exposure

-slow

-specific

-memory response

Branches of adaptive immune system

Humoral (antibody-mediated) B lymphocytes 

Cellular (cell-mediated) T lymphocytes 

Humoral immunity origin and maturation

bone marrow 

Humoral immunity site of activation

spleen/lymph nodes

Does humoral require APC

No

Humoral effector cell

plasma cells

Does humoral produce memory

Yes

Cell-mediated origin

bone marrow

cell-mediated maturation

thymus

cell-mediated activation site

spleen/lymph nodes

does cell-mediated require APC

Yes

Cell-mediated effector cell

Helper T, Cytotoxic T

Does cell-mediated produce memory

Yes

Humoral immunity

mark target for destruction

extracellular targets

Cellular immunity

Directly kill (T lymphocytes)

Indirectly releasing chemicals (helper T lymphocytes)

Intracellular targets 

Two processes in maturation

immunocompetence

self-tolerance 

immunocompetence

recognize one particular antigen

self-tolerance

lymphocytes must not kill own cells

Clonal selection

lymphocyte selected to differentiate into active cell by binding to specific antigen 

clonal expansion

after selection and activation, lymphocyte proliferates (exact copies)

effector cells

fight infections

memory cells

respond quicker second time it is encountered

antigen

anything that provokes an immune response

non-self antigens 

pathogens 

allergens

self-antigens

body’s immune system reacts to own tissues

Antibody structure

T or Y shape

2 heavy chains

2 light chains

variable regions (antigen binding site) 

constant regions (antibody class)

IgM

First antibody released

agglutinating 

IgG

Secondary responses

cross placental barrier 

IgA

secretions

IgE

allergies and parasitic infections

Antibody functions

neutralization

agglutination 

complement fixation 

neutralization

block receptor site

agglutination

clumping

complement fixation

main antibody defense against cellular antigens

opsonization 

allows for easier phagocytosis 

T cells provide defense against

intracellular antigens

CD4+ T helper cells

activate B cells and other T cells

T and B proliferation 

Secrete cytokines 

HIV invades 

cytokines

communicators that cause inflammation (interferons, interleukins, TNF)

CD8+ cytotoxic T cells

directly attack and kill

in blood, lymph, and lymphoid organs 

Tc cells target

virus infected cells

cells with intracellular bacteria or parasites 

cancer cells

foreign cells 

What do Tc cells release

perforins

granzymes 

What do granzymes do

stimulate apoptosis

perforins

create holes so granzymes can enter target cell

APCs types

Macrophages

Dendritic cells 

B lymphocytes 

APC presentation

antigen to MHC molecule on APC then to T lymphocytes

What cells require antigen presentation

T cells

MHC molecules

set of genes that encode cell surface proteins

MHC task 

alerts immune cell if the antigen belongs to the body or not 

T lymphocytes can recognize only antigens that are

presented on MHC proteins

Class l MHC proteins

All cells besides RBC

Cytotoxic 

Class ll MHC proteins

Helper 

Displayed by APCs

Belong to self-help with immune response 

Infected cell can only display

MHC l

APC can display

MHC l and ll

active immunity

individual must provide the immunity

passive immunity 

individual provided with the immunity 

natural

without medical intervention

artificial

with medical intervention

Natural active immunity

get a cold, fight off

Artificial active immunity 

vaccines 

Natural passive immunity

Breastfeeding/placenta

Artificial passive immunity

Antibiotic

allograft

transplant from same species

Success of transplants depends on 

similarity of tissues 

Death of transplant recipients

body cant protect from foreign agents because of immunosuppression

Graft rejection hypersensitivity

Type lV response

immunodeficiency

impair function or production of immune cells

congenital or acquired

Severe combined immunodeficiency syndrome 

Deficit in B and T cells 

AIDS

HIV cripples the immune system and interferes with helper T cells

weight loss, night sweats, opportunistic infections 

Leukocytes (WBC)

defense against disease