PHSC1312 Microbiology/Immunology Lecture 2 Host Immunity - Organs, Tissues, & Cells

immune system

includes organs, tissues, cells, and molecules responsible for immunity

innate and adaptive

two compartments of immune system that contribute to host immunity

innate immunity

cellular and biochemical defense mechanism in place at birth that responds to antigens in a generic way

genetic, generic and rapid response, barriers

characteristics of innate immunity

at birth

innate immunity development

physical and chemical barriers, cells, blood proteins

components of innate immunity

adaptive immunity

specific immunity with memory

acquired with exposure

adaptive immunity development

specificity

ability to recognize antigen based on epitopes on them

epitopes

short stretches or structural motifs on antigens

memory

ability to respond more vigorously to repeated exposures to same microbe

5-7 days

How long does it generally take the adaptive immunity to recognize?

cells and humoral

two components to adaptive immunity

primary

sites where leukocytes and lymphocytes develop

bone marrow

in long bones, B and T cells start here

thymus

where T cells develop

secondary

other sites where leukocytes don't develop

spleen, lymph nodes, lymph nodules, lymphatic vessels

secondary organ/tissue examples

return bulk of fluids back to circulation

secondary purpose for lymphatic system

lymphoid tissues, nodes, and nodules

Where do immune cells reside?

lymph nodes

function as filter sites for lymph

monitor peripheral infections and respond before infections reach vital organs

How do lymph nodes function as filter sites for lymph fluid

afferent vessel

lymphatic vessel with lymph flowing into lymph node

efferent vessel

lymphatic vessel with lymph flowing out of lymph node

lymph nodes, spleen, respiratory tract, tonsils, along digestive, urinary, and reproductive tracts

Where are lymphoid/lymphatic nodules found?

lymphatic vessels

return excess fluid to bloodstream, transport hormones, nutrients, and wastes, maintain and distribute lymphocytes and other lymphoid cells

right lymphatic duct

empties into right subclavian vein, lymph from upper right side of body

thoracic duct

empties into left subclavian vein, lymph from upper left side and lower part of the body

subclavian vein

Where do the lymphatic and thoracic ducts empty into?

lymphedema

blockage of lymph drainage from a limb that causes severe swelling and interferes with immune system function

blockage of lymph drainage

What causes lymphedema?

severe swelling and immune system interference

What does lymphedema cause?

all nucleated cells

Which cells express MHC I?

hemoglobin

Which cells don't express MHC I?

major histone compatibility

What does MHC I stand for?

only antigen presenting cells

Which cells express MHC II?

dendritic cells, macrophages, B cells

three types of antigen presenting cells

leukocytes

function to defend host against pathogens, remove toxins and wastes, contribute to inflammation, and attack abnormal or damaged cells

leukocyte counts

subset of results from a complete blood count (CBC) that indicates infection, inflammation, and allergic reactions

infection, inflammation, allergic reaction

What does leukocyte count indicate?

3.4-9.6 billion cells/L

normal leukocyte count range

leukopenia

low white blood cell count

leukocytosis

high white blood cell count

polymorphonuclear leukocytes

another name for neutrophils

phagocytic, first responders, most abundant, important in bacterial infections

neutrophil characteristics

pale cytoplasmic granules

What do neutrophils have with lysosomal enzymes and bactericidal compounds?

lysosomal enzymes and bactericidal compounds

What do neutrophils have inside their granules?

DNA nets

What do neutrophils have to trap pathogens?

pus and wound repair

What do neutrophils contribute to?

eosinophils

perform phagocytosis of bacteria, protozoa, and cellular debris

bacteria, protozoa, and cellular debris

Eosinophils perform phagocytosis of what?

releasing toxic nitric oxide and cytotoxic enzymes

How do eosinophils attack large parasites?

allergens

What are eosinophils sensitive to?

peripheral mucosal tissues

Where are eosinophils present?

respiratory, GI, and genitourinary tracts

peripheral mucosal tissues

basophils

cross capillary endothelium and accumulate in damaged tissues; release histamine and heparin

capillary endothelium

What do basophils cross?

damaged tissues

Where do basophils accumulate?

histamine and heparin

What do basophils release?

histamine

dilates blood vessels, released by basophils

heparin

prevents blood clotting, released by basophils

mast cells and basophils

Which cells contain granules with similar capabilities?

mast cells

recognize and respond rapidly to microbes by producing cytokines and other mediators that induce inflammation

inflammation

What do mast cells induce?

cytokines and lipid mediators prostaglandinsm

What do mast cells produce to induce inflammation?

histamine and proteolytic enzymes

contained in mast cell cytoplasmic granules

proteolytic enzymes

kill bacteria or inactivate bacterial toxins

macrophages

phagocytic cells with enzymes and reactive chemicals to kill microbes

to dilate blood vessels and recruit more immune cells

Why do macrophages secrete cytokines?

primed T cells

What do macrophages activate?

angiogenesis and fibrosis

What do macrophages stimulate?

angiogenesis

new blood vessel growth

fibrosis

synthesis of collagen-rich extracellular matrix

naive T cells

What do dendritic cells activate?

epithelia and most body tissues

Where are dendritic cells present?

pamps and damps

What are dendritic cells sensors for?

lymphocytes

subtype of leukocytes; continuously migrate in and out of the bloodstream

organs of lymphatic system and connective tissues other than blood

Where are lymphocytes?

T cells, B cells, and natural killer cells

three classes of lymphocytes

cell-mediated

What type of immunity do T cells have? (specific to adaptive)

attack cells or stimulate B cells to produce antibodies

T cell role

humoral

What type of immunity do B cells have? (specific to adaptive)

make antibodies and differentiate into plasma cells

What do B cells do?

Natural killer cells

cells that detect and destroy infected or abnormal cell

perforin and granzyme

What do natural killer cells secrete?