LEC 5

immune system

• Role is to provide defense against harmful substances

▪Every time we get exposed to harmful agents such as bacteria, viruses, and other foreign substances, our body’s immune system make sure that we would not get sick from this exposure

T cells

Activated macrophages, assist b cells

stimulation of the stress response

However, when the immune system fails to initially isolate and kill the intruding MCG allowing it to progress into the body, manifestations (signs and symptoms) of infection occur as a result of the

allergies

Under normal conditions, the immune system is protective but it can also cause some adverse effects when overstimulated such as in the case of———-

autoimmune diseases

This protective effect is due to the ability of the immune system to discriminate between self from non-self which allows it to recognize and react appropriately to different classes of pathogens and altered cells (e.g. malignant cells). However, without this ability to discriminate self from non-self, conditions such as

antigen/immunogen

a substance that elicits an immune response

antibodies/immunoglobulins

proteins produced in response to invasion of antigens

skin and mucous membranes

Serve as protective barrier as part of the first line of defense of the immune system

gastrointestinal tract

Secrete digestive enzymes as part of the first line of defense

lymph tissues

House lymphocytes  as part of the third line of defense. Found in the bone marrow, thymus, lymph nodes, spleen, tonsils, adenoids, appendix, Payer’s patches, and mucous membranes

immune cells

Includes phagocytes, natural killer cells, T-cells, B-cells

Skin, mucus, tears, sweat, digestive enzyme

first line of defense

Granulocytes and macrophages

second line of defense

Sensitized T lymphocytes and antibodies

third line of defense

Innate/ natural / native/ nonspecific immunity

action of phagocytes and natural killer cells are not directed to cell.

phagocytes

scavenge and engulf; secrete complement and cytokines

complements

secreted by phagocytes that disarm microbes either by making them more susceptible to phagocytosis or by puncturing the cell membrane

cytokines

secreted by phagocytes, bind to receptors on target cells, and stimulate growth and proliferation

adaptive/ acquired/specific immunity

action of T-cells and B-cells recognizes specific antigens.

cell mediated or cellular immunity

cells travel to invade the microorganisms in the invasion site and wage a battle against them, exercised by the T-cells

humoral immunity

cells’ secretions wage a battle against the invaders. B-cells respond by secreting antibodies

active

Long-lasting adaptive immunity acquire through exposure to antigens either through immunization or actually having the disease

passive

Short-term adaptive immunity acquire through transfer of protective antibodies against an antigen such as an infant receiving antibodies in utero and through breast milk and injection of hyperimmune serum

helpers

Alert other T-cells and B- cells to prepare a response

inducers

Stimulate precursor cells in thymus to mature into T- cells

killers

Destroy invading organism

suppressors

Turn off immune response

b-cells

• Make foreign organism an easy target

• kill foreign organism directly

white blood cells

Granulocytes and macrophages are found in the

granulocytes

engulf foreign organism entering the body through phagocytosis

macrphages

engulf foreign organism through phagocytosis. It displays antigens on their surface that activates lymphocytes.

monokine

On the other hand, macrophages secrete —- that activates lymphocytes, suppress appetite, and induce malaise and fever

adaptive immunity

immunity that is specific for particular antigens; it adapts to antigens in an individual's environment

and is characterized by "memory" for particular antigens. Also called acquired

Immunity.

acute-phase proteins

plasma proteins released from the liver

at the onset of acute infection. An example is C-reactive protein, which is considered one of the main indicators of severe infection and has

antimicrobial effects.

allergen

any substance that triggers an inappropriate

immune response.

allergy

an excessive and inappropriate immune reaction to a harmless substance.

autoimmune diseases

diseases characterized by an attack of immune defenses on the body's own cells.

b cell

lymphocyte that produces antibodies.

cell mediated immunity

immunity conferred by T cells and macrophages.

cytokines

signaling proteins produced by the body's cells; those produced by white blood cells regulate immune cell development and immune responses.

humoral immunity

immunity conferred by B cells, which produce and release antibodies into body fluids.

• humor = fluid

hypersensitivity

immune responses that are excessive or inappropriate. One type of —- is allergy

immune system

the body's defense system against foreign

substances.

immunoglobulins

large globular proteins produced by B cells that function as antibodies.

inflammation

a nonspecific response to injury or infection; a type of innate immune response.

innate immunity

immunity that is present at birth, unchanging throughout life, and nonspecific for particular antigens; also called natural Immunity.

leukocytes

blood cells that function in immunity; also called white blood cells.

lymph

the body fluid carried in lymphatic vessels; lymph is collected from the extracellular fluids of body tissues and ultimately transported to the bloodstream.

lymphatic vessels

vessels through which lymph travels.

lymphocytes

white blood cells that recognize specific antigens and therefore function in adaptive immunity; include T cells and B cells.

lymphold tissues

tissues that have roles in immunity.

lysozyme

an enzyme with antibacterial properties; found in immune cells and body secretions such as tears, saliva, and sweat.

macrophages

monocytes that have left. circulation and settled in a tissue, where they serve as scavengers and activate the immune response

monocytes

cells released from the bone marrow that move into tissues and mature into macrophages.

natural killer cells

lymphocytes that confer nonspecific immunity by destroying a wide array of viruses and tumor cells.

neutrophils

the most common type of white blood cell. —— destroy antigens by phagocytosis.

phagocytes

white blood cells (primarily neutrophils and macrophages that have the ability to engulf and destroy antigens) phagein= to eat

phagocytosis

the process by which phagocytes engulf and destroy antigens.

t cell

a lymphocyte that attacks antigens; functions in cell mediated immunity.

copper

Inc. susceptibility to infection

Dec. antibody production

Impaired phagocyte function

Dec. T cell production, particularly that of T helper cells

Dec. T cell count

Dec. production of IL-2

Inc. B cell count

Fewer circulating granulocytes/neutrophils

Dec. neutrophil respiratory burst in mice

Impaired T cell function

iron

T cell and phagocyte abnormality

Dec. cytokine release

Dec. inflammatory response

Impaired neutrophil and macrophage cytotoxicity

Dec. allograft rejection

Lymphoid tissue atrophy

Dec. T cell count

Dec. antibody production

Inhibits proliferation of T helper 1 (Th1) cells

Removal of stores decreases t cell proliferation and differentiation

Chronic inflammation is associated with low serum iron and high levels of iron stores

magnesium deficiency

Inc. thymic cellularity

Creation of an oxidative environment

Dec. acute phase molecules

Inc. numbers of inflammatory cells (eosinophils)

Inc. IL -1, Il-6, TNF and histamine levels

Dec. complement activity

selenium

Dec. resistance to infection

Dec. lymphocyte proliferation

Inc. risk of viral infection

Dec. antibody synthesis

Dec. cytotoxicity

Dec. cytokine secretion

Dec. cell-mediated cytotoxicity

zinc

Thymic atrophy, Dec. numbers of T and B cells, Dec. thymic hormone release, Dec. T cell response to mitogens, Dec. T cell maturation, Red. NKC activity, Dec. cytolytic T cell response, Dec. T cell help to antibody production, Inc. corticosteroid production

Disturbances in Ca/P metabolism

Enlarged adrenal glands, Depressed delayed-type hypersensitivity response, Suboptimal zinc during in utero development of mice causes persistent states of immunodeficiency that can be transferred to subsequent generations, Depressed concentration of serum albumin, prealbumin and transferrin, Problems with regulation of blood sugar, May accelerate progression to aids

vit A deficiency

Dec. number of leucocytes

Dec. CD4 (T helper cell membrane glycoprotein) count

Dec. levels of circulating complement

Impaired T cell function

Inc. severity of infection

Dec. resistance to immunogenic tumors

Dec. lymphoid organ weight

Dec. antigen-specific IG-G and IG-E responses

Induces hypergammaglobulinemia

May affect vertical transmission of HIV

May affect progression to AIDS

pyridoxine

Lower lymphoid tissue weights

Dec. T cell count

Dec. proliferative response to mitogens

biotin

Lower thymic weight

Dec. lymphocyte proliferation

Dec. antigen-specific antibody response

Dec. lymtphocyte-mediated suppressor

pantothenic acid/ vit b5 def

dec. antibody response

thiamin deficiency

Dec. antibody response

Premature thymic atrophy

Dec. mobility of polymorphonuclear leukocytes

riboflavin

Inc. polymorphonuclear leukocytes

Dec. peripheral blood mononuclear cells

Lower thymic weight

Dec. antibody response

Inc. susceptibility to infection

vit c deficiency

Dec. resistance to infection

Fewer delayed-type hypersensitivity reactions

Dec. phagocytosis

Dec. phagocyte mobility

Red. Skin allograft rejection

Impaired wound healing

protein

Impaired humoral immunity

vitamin e deficiency

Dec. leukocyte production

Unaffected or enhanced NKC activity

Dec. phagocytosis and chemotaxis by polymorphonuclear leukocytes and macrophages

Red. Lymphocyte proliferation

energy

PEM and obesity both depresses immune functions

PEM impairs all components of the immune response

Obesity lowers T and B cells’ responses

fats

If high , can impair immune response

Specific fatty acids affect the fluidity of cell membrane which affects the structures on the cell surfaces that have receptors and respond to immunologic stimulations

Thinned, with less connective tissue

skin

gastrointestinal tract

Likelihood bacterial translocation compounded when intestines are injured

mucous membranes

Microvilli flattened; antibody secretions reduced

lymph tissue

Thymus gland, lymph nodes, and spleen reduced in size; T cells  are depleted of lymphocytes.

phagocytosis

Kill time delayed

cell-mediated immunity

circulating t cells reduced

humoral immunity

Circulating immunoglobulin levels normal; antibody response may be impaired

VIT B12 and folate

Dec. respiratory burst

Dec. phagocytosis by peripheral mononuclear cells

Dec. CD4 (T helper cell) count

Depressed phagocytic function

Dec. delayed-type hypersensitivity response

Dec. T cell proliferation to phytohemaglutinin stimulation

May accelerate progression to AIDS

May cause or increase the severity of AIDS dementia comple

B cells

Secretes and produce antibodies

Natural killer cells

Destroy virally infected cells

Monocytes/macrophages

Present antigen fragments to t cells, engulf pathogens and cellular debris

Neutrophils

Engulf pathogens and cellular debris

Eosinophils

Release proteins that damage paradited , surpress inflammatory reactions

Basophils

Release mediators that regulate inflammation

Mast cells

Release mediators that regulate inflammation

Platelets

Have primary role in blood clotting, release mediators that regulate inflammation