Micro Immunity-Specific, Non-specific, & Disorders

macrophages

"big eaters" destroy not only microorganisms but also larger particles such as debris left from neutrophils that have died ingesting bacteria -they take longer than neutrophils to reach an infection site but they arrive in larger numbers -Fixed macrophages: remain stationary in tissues and have different names depending on the tissue they live in -Wandering macrophages: like neutrophils, circulate in blood, moving into tissues when microbes and other foreign materials are present BUT can live for months or years -critical in both innate and adaptive defenses

opsonization

(immune adherence) -antibodies called opsonins bind to and coat the surface of the infectious agent which are recognized by phagocytes as signal to eat em up

IgE

(reagin) -has a special affinity for receptors on the plasma membranes of basophils in the blood or mast cells in the tissues. binds to these cells leaving antigen-binding sites free to bind antigens to which humans can develop allergies (drugs, pollens, foods) -causes basophils or mast cells to secrete histamine -found mostly in body fluids and skin, rare in blood

acute inflammation

-battle is usually won by the host In infections, acute inflammation fx is: 1. kill invading microbes 2. clear away tissue debris 3. repair injured tissue

IgD

-like IgM found mainly on B cell membranes and rarely secreted -it can bind to antigens but its fx is unknown. may help initiate immune responses and some allergic reactions. -levels rise in autoimmune conditions

IgM

-monomer on surface of B cells and secreted at pentamer by plasma cells -1st antibody secreted into blood during early stages of primary response -it binds to antigens -it activates the complement system and causes organisms to clump together -1st antibody formed in life, synth by fetus

nonspecific defenses fight a pathogen entering the body through: inhalation into your lungs

-mucus -macrophages

secondary response

-occurs when antigen is recognized by memory cells -much faster than primary response -some memory cells divide rapidly, producing plasma cells other proliferate and form more memory cells -same IgM and IgG are produced but IgM is smaller qty and length of time while IgG is larger qty and sooner

formed elements

-other 40% of blood Includes: -erythrocytes RBC -platelets -leukocytes WBC

interferon

-protein responsible for viral interference or virion replication -sends signals to other cells to keep virus from infecting them -after infection the cell synthesizes and secretes interferon which diffuses to adjacent cells and binds to their surfaces. -this binding stimulates cells to transcribe specific genes into mRNA molecules which are then translated to produce many new antiviral proteins

T lymphocytes or T cells

-stem cells migrate to the thymus where they undergo differentiation into these thymus-derived cells -in adulthood, when the thymus becomes less active, differentiation of T cells still occurs in the thymus but at a lower frequency -found in all tissues that contain B cells and account for about 3/4 of the lymphocytes circulating in the blood -subsequent differentiation of T cells produces which then migrate among lymphatic tissues and blood: 1. cytotoxic (killer) T cells 2. delayed-hypersensitivity T cells 3. helper T cells 4. regulatory T cells

nonspecific defenses fight a pathogen entering the body through: small cut on your hand

-sweat & sebum combine to inhibit growth on the skin -blood flushes microorganisms out -constriction of ruptured blood vessels and clotting seals off injured area -phagocytes at portal of entry or circulating in blood or lymph

granulocytes

-type of leukocyte have granular cytoplasm and irregular shaped, lobed nucleus -derived from myeloid stem cells in bone marrow -Include: basophils, mast cells, eosinophils, neutrophils

natural killer NK cells

type of lymphocyte whose activity is greatly increased by exposure to interferons and cytokines. -most likely recognize specific glycoproteins on cell surface of virus infected cells and then secrete cytotoxic proteins that trigger the death of the infected cell -1st line of defense against viruses until the adaptive immune system can become effective days later

4 steps process of phagocytosis

used when infection occurs to destroy invading microbes 1. find 2. adhere to 3. ingest and 4. digest the microbes

histamine

when cells are damaged this substance is released from basophils and mast cells which diffuses into nearby capillaries and venules causing the walls of these vessels to dilate and become more permeable -this dilation increases the amt of blood flowing to the damaged area and it causes the skin around wounds to become red and warm to the touch. -because the vessel walls are more permeable, fluids leave the blood and accumulate around the injured cells causing edema -blood delivers clotting factors, nutrients, and other substances to the injured area and removes wastes and some excess fluids. it also brings macrophages which release cytokines. -some cytokines are chemokines and attract other phagocytes and another cytokine called tumor necrosis factor alpha which causes more vasodilation and edema -can also cause red, watery eyes and runny nose of hay fever and breathing difficulties in certain allergies

Fab (antibody binding fragment) and Fc (crystallizable fragment)

when the antibody is cleaved with the enzyme papain at the hinge region, two Fab pieces and one Fc piece result. The Fab fragment binds to the epitope. The Fc region formed by parts of the H chains in the tail of the Y has a site that can bind to and activate complement, participate in allergic reactions, and combine with phagocytes in opsonization

pluripotent stem cell

where all formed elements are derived (RBC, platelets, WBC)

diapedesis

within an hour after the inflammatory process begins, phagocytes such as neutrophils start to arrive at the injured or infected site -this allows neutrophils to congregate in tissue fluids in the injured region

natural killer cells (NK cells)

a few lymphocytes that cannot be identified as either B or T cells are found in tissues circulating in blood -they nonspecifically kill cancer cells and cells infected with viruses w/o having to utilize the specific immune response. they "naturally" kill cells by releasing various cytotoxic molecules, some of which create holes in the target cell's membrane, leading to lysis. others enter the target cell and fragment its nuclear DNA, causing apoptosis (programmed cell death) -also enhanced by interferons

specificity

ability of immune system to react in different ways to each foreign substances -due to specificity, each reaction is directed toward a specific foreign antigen and the response to one antigen generally has no effect on other antigens

pus

accumulation of dead phagocytes, injured or damaged cells, remains of ingested organisms and other tissue debris

MHCII (major histocompatibility complex II

after the B cell has bound antigen to antibody it takes both into the cell where it "processes" the antigen by breaking it into short fragments which bind to MHCII molecule on the surface of the B cell. this is called presenting the antigen and macrophages and dendritic cells do this as well. -T cells recognize the antigen plus MCHII and become activated to produce interleukin 2 (IL-2). -The direct contact of a T helper cell with the antigen-presenting B cell stim the B cell to proliferate further and form B memory cells. -w/o T helper cell contact, no B memory cells are formed

artificially acquired passive immunity

antibodies made by other hosts are introduced to a new host. EX: rattlesnake antivenin injection -these antibodies and the immunity they confer persist for a few weeks to months and are destroyed by the host and the host's immune system cannot make new ones

agglutination

antigen-antibody reactions result in this sticking together of microbes

neutralization

bacterial toxins are inactivated with this form of antigen-antibody complex -IgG is the main neutralizer of bacterial toxins -this reaction stops the toxin from doing further damage to the host -it does not destroy the organisms that produce the toxin, just inactivates (can also inactivate viruses) -IgM, IgG, and IgA are all effective neutralizers of viruses

immunoglobulins (Ig)

basic units of antibodies -Y shaped protein molecules composed of four polypeptide chains held together by disulfide bonds -two identical light (L) chains -two identical heavy (H) chains -the single Y shaped molecule is called a monomer -constant region determines the particular class -variable region enables molecule to bind with particular antigen

anti-histamines

block the released histamine from reaching its receptors on target organs

inflammation

body's response to tissue damage from microbial infection or mechanical injury, heat and electricity (burns), UV light (sunburn), chemicals and allergies 1. calor-increase in temp 2. rubor-redness 3. tumor-swelling 4. dolor-pain at infected or injury site

humoral and cell-mediated immunity

both responses have certain common attributes that enable them to confer immunity: 1. recognition of self vs nonself 2. specificity 3. heterogenicity 4. memory -fx depends on the ability of B cells to recognize specific antigens and on their ability to initiate responses that protect the body against foreign agents

Humoral immunity

carried out by antibodies circulating in the blood. when stim by an antigen, B cells initiate a process that leads to the release of antibodies. -it is most effective in defending the body against foreign substances outside of cells such as bacterial toxins, bacteria, and viruses before these agents enter cells

the immune system

consists of various cells, especially lymphocytes and organs such as the thymus gland, that help provide the host with specific immunity to infectious agents

tonsils

contribute to immune defenses, contain B cells and T cells

mucous membrane or mucosa

covers those tissues and organs of the body cavity that are exposed to the exterior -physical barrier

passive immunity

created when ready-made antibodies are introduced into the body. the host's own immune system does not make antibodies

phagosome

cytoplasmic vacuole formed by pseudopodia, finger like extensions, that come off the cell membrane of the phagocyte. -used on microbes that are too sly for phagocyte to adhere to and must be captured using the complement system

leukocytes

defensive cells that are important to both adaptive and innate host defenses -divided into two groups: granulocytes and agranulocytes

lymphocytes

derived from lymphoid stem cells of bone marrow -contribute to adaptive host immunity -circulate in blood and found in large numbers in lymph nodes, spleen, thymus, tonsils -give rise to humoral and cell-mediated immunity

monocytes

derived from myeloid stem cells in bone marrow and move to blood -important components in innate host defenses and are phagocytes -mature into macrophages when they move from the blood into tissues

genetic immunity (innate immunity)

exists due to genetically determined characteristics (includes species immunity) -includes the ability of an organism to recognize pathogens when phagocytes and macrophages are activated

clonal selection hypothesis

explains one way in which the immune system might distinguish self from nonself -states: embryos contain many different lymphocytes, each genetically programmed to recognize a particular antigen and make antibodies to destroy it. if a lymphocyte encounters and recognizes that antigen after development is complete, it divides repeatedly to produce a clone, a group of identical progeny cells that make the same antibody. if, during development in the bone marrow (B cells) or thymus (T cells), it encounters its programmed antigen as part of a normal host substance (self), the lymphocyte is somehow destroyed or inactivated. This mechanism remove lymphocytes that can destroy host tissues and thereby creates tolerance for self. it also selects for survival lymphocytes that will protect the host from foreign antigens

colostrum

first fluid secreted by mammary glands after birth. deficient in many nutrients compared to milk it contains large quantities of antibodies that enter the infants blood and protect infant for short time (approx 6 months)

lymph nodes

fluid passes through these as it travels through lymph vessels, filtering foreign material and allowing contact with mature T cells -most numerous in the thoracic (chest), neck, armpits, and groin -anatomically similar to the spleen: encapsulated, lobed and well supplied with blood and lymphatic vessels , spleen also contains T cells

non-self

foreign substances

neutrophils

guard blood, skin and mucous membranes against infection -phagocytic and respond quickly where tissue injury occurs -create cytotoxic substances capable of killing bacteria and other engulfed pathogens -programmed to die after 1-2 days and are killed in the process of killing microbes and form pus

adaptive (acquired) immunity

immunity obtained in some manner other than by heredity. can be naturally or artificially acquired

primary response

in humoral immunity, this response to an antigen occurs when the antigen is 1st recognized by host B cells -after recognizing the antigen, B cells divide to form plasma cells which begin to syn antibodies -in a few days antibodies begin to appear in the blood plasma and concentration increases over 1-10 weeks -1st out are IgM which bind direct to foreign substances -cytokines trigger B cells to switch to making plasma cells that make IgG instead of IgM -memory cells are also produced along with plasma cells

phagocyte uses which process to kill

intracellular killing, the microbe is degraded within a defense cell

cell-mediated immunity

is carried out by T cells. it occurs at the cellular level, esp in situations where antigens are embedded in cell membranes or are inside host cells and are thus inaccessible to antibodies -most effective in clearing the body of virus-infected cells but also may participate in defending against fungi and other eukaryotic parasites, cancer, and foreign tissues such as transplanted organs

species immunity

is common to all members of a species

titer

is the quantity of a substance needed to produce a given reaction. (concentrations of antigens and antibodies) -an antibody titer is the qty required to bind to and neutralize a particular qty of an antigen

agranulocytes

lack granular cytoplasm and have round nuclei -include: monocytes and lymphocytes

epitopes or antigenic determinants

large complex proteins can have several of these. Areas on the molecule to which antibodies can bind

plasma cells

large lymphocytes that synthesize and release many antibodies like those on their membranes. while active, a single plasma cell can produce as many as 2000 antibodies per second

plasma

liquid in the blood -is 60% of blood

spleen

located in the URQ of abd cavity, largest of the lymphatic organs -anatomically similar to lymph nodes -it does not filter material -contains many phagocytes in its sinusoids that engulf and destroy worn-out erythrocytes and microorganisms -it also contains B cells and T cells

lymphatic vessels

lymphatic capillaries join to form these. -lymphatic system has three major fx: 1. collect excess fluid from spaces between body cells 2. transports digested fats to the cardiovascular system 3. provides many of the innate and adaptive defense mech against infection and disease

B lymphocytes or B cells

lymphocytes that are processed and mature in tissue and are referred to as bursal-equivalent tissue -differentiate in bone marrow -functional B cells are found in all lymphoid tissues: lymph nodes, spleen, tonsils, adenoids, gut-associated lymphoid tissues (GALT) which are lymphoid tissues in the digestive tract including the appendix and Peyer's patches of the small intestine -each kind carries its specific antibody on its membrane and can bind immediately to a specific antigen

naturally acquired adaptive immunity

most often obtained by having a specific disease. -immune system responds to antigens, activates T cells, produces antibodies and initiates other specific defenses that protect against future invasions by the same agent -can be naturally acquired from antibodies transferred to fetus across the placenta or to infant in colostrum

thymus gland

multilobed lymphatic organ located beneath the sternum -present at birth, grows until puberty, then atrophies and is mostly replaced by fat and CT by adulthood -produces T cells which regulate development of B cells into antibody producing cells and sub-populations of T cells can kill virus-infected cells directly

self

normal host substances

artificially acquired adaptive immunity

obtained by receiving an antigen by the injection of vaccine or immune serum that produces immunity

phagolysosome

one of many mechanisms for phagocytic cells to digest and destroy ingested microbes -one mech uses lysosomes found int the phagocytes cytoplasm. these organelles, which contain digestive enzymes and small proteins called defensins, fuse with the phagosome membrane to form these

antibody

one of the most significant responses of the immune system to any foreign substance is to produce these -it is a protein produced in response to an antigen that is capable of binding specifically to the antigen

bradykinin

pain associated with tissue injury is thought to be due to the release of this small peptide at the injured site -its effects are intensified by prostaglandins

cytokines

phagocytes at the site of infection release these chemicals, small soluble proteins that have specific roles such as activation of cells involved in inflamm response

phagocytosis

phagocytes digest and generally destroy invading microbes and foreign particles

eosinophils

present in large numbers during allergic reactions and worm infections -also detoxify foreign substances and help turn off inflamm reactions by releasing histamine-degrading enzymes

mast cells

prevalent in connective tissue and alongside blood vessels, also release histamine and associated with allergies

naturally acquired passive immunity

produced when antibodies made by a mother's immune system are transferred to her offspring. EX: receive antibodies from colostrum

anamnestic (secondary) response

prompt response due to "recall" by memory cells

complement or the complement system

refers to a set of more than 20 large regulatory proteins that play a key role in host defense -produced by the liver and circulate in plasma in an inactive form -has nonspecific effects and exerts the same defensive effects regardless of which microorganism has invaded the body General fx: 1. enhance phagocytosis by phagocytes 2. lyse microorganisms, bacteria, and enveloped viruses directly 3. generate peptide fragments that reg inflamm and immune responses -also response immediately long before adaptive defenses are mobilized

basophils

release histamine, a chemical that helps initiate the inflamm response

dendritic cells

resemble dendrites of nerve cells in appearance -phagocytic and involved in initiating the adaptive defense response

effects of the compliment cascade

results in: 1. opsonization 2. inflammation 3. membrane attack complexes

6 nonspecific defenses

1. Physical barriers: skin, mucous membranes and the chemicals they secrete 2. Chemical barriers: antimicrobial substances in body fluids such as saliva, mucus, gastric juices and iron limitation mechanisms (transferrin protein binds to free iron in blood-bacteria require iron as a cofactor for some enzymes) 3. Cellular defenses: consists of certain cells that phagocytize invading organisms 4. Inflammation: reddening, swelling, temp increase in tissue at sites of infection 5. Fever: body temp elevated to kill invading agents or inactivate their toxic products 6. Molecular defenses: interferon and complement, destroy or impede invading microbes

innate defenses or nonspecific defenses

1st Line of defense -those that act against any type of invading agent. Often function is performed before adaptive body defense mechanisms are activated -The innate system's action is necessary to activate the adaptive defense system

Adaptive defenses or specific defenses

2nd line of defense -respond to particular agents called antigens. Viruses and pathogenic bacteria have molecules in or on them which serve as antigens. Adaptive defenses respond to antigens by producing protein antibodies or activating lymphocytes. -This type of defense is most useful against succeeding invasions than initial invasions thanks to memory cells

IgA

small amts in blood and large amts in body secretions such as tears, milk, saliva, and mucus, attached to linings of digestive, respiratory and genitourinary systems -main fx is to guard entrances to the body by binding antigens on microorganisms before the invade tissues -also activates complement which helps kill microorganisms -abundant in colostrum to protect infant from intestinal pathogens -some individuals unable to make secretory form of IgA, one effect of which is getting more cavities

hapten

small molecule that can act as an antigen if it binds to a larger protein molecule. -they act as epitopes on the surfaces of proteins -sometimes bind to body proteins and provoke an immune response -neither the hapten nor the body protein alone can act as an antigen but combined they can EX: penicillin molecules can bind with protein molecules and elicit an allergic reaction which in reality is a hypersensitivity reaction of the immune system

antigen

substance the body identifies as foreign and toward which it mounts an immune response-often it is referred to as an immunogen -found on the surfaces of viruses and all cells, including bacteria, other organisms and human cells -determining how the human body responds to these different antigenic determinants is important in making effective vaccines -EX: antigens on surfaces of RBC determine blood types, antigens on other cells determine whether a tissue transplanted from another will be rejected

fever

systemic increase in body temp which often accompanies inflamm -caused by many pathogens, by certain immunological processes (such as reactions to vaccines), and by nearly any kind of tissue injury, even heart attacks -most often caused by a pyrogen Benefits of fever: 1. it raises the body temp above optimum temp for growth of many pathogens, at higher temps some microbial enzymes or toxins may be inactivated 2. induces rest by host to divert energy to healing 3. it can heighten the level of immune responses by increasing the rate of chem reactions in the body 4. liver stores nutrients (Fe/Zn) that bacteria need

immunity

the ability of an organism to recognize and defend itself against infectious agents

sensitizes

the binding of an antigen sensitizes or activates the B cell and causes it to divide many times. some of the progeny are memory cells but most are plasma cells

IgG

the main class of antibodies found in the blood, 20% of all plasma proteins -produced in largest quantities during secondary response -the antigen-binding sites of IgG attach to antigens on microorganisms and their tissue-binding sites attach to receptors on phagocytic cells, thus, as a microorganism is surrounded by IgG, a phagocytic cell is brought into position to engulf the organism -only Ig that can cross the placenta and is also found in milk and colostrum

chemotaxis

the movement of cells toward a chemical stimulus. attracted to site of infection by cytokines

memory cells

these are produced by the immune system when it encounters an antigen along with the antibodies. they stand ready for years or decades to quickly initiate antibody production -enable a much more rapid response to subsequent exposure to same antigen