NOTES: Immune Responses (UNIT 10 part 4)

PRIMARY IMMUNE RESPONSE • PRIMARY IMMUNE RESPONSE: the first reaction / response to an antigen (first exposure)  During this response, antibodies are produced for several weeks  Antibodies first show up within 5-10 days  As a result, some B cells will remain dormant as MEMORY CELLS

SECONDARY IMMUNE RESPONSE • SECONDARY IMMUNE RESPONSE: the second response (exposure) to an antigen Rapid response due to memory cells produced during the first exposure  Antibodies produced within a day or two

CLASSIFICATION OF IMMUNITY 1) ACTIVE IMMUNITY ● A result of direct exposure to the antigen ● when the person produces an immune response (including memory cells) to the antigen ● Long-lasting (due to memory cells)

ACTIVE IMMUNITY… NATURALLY ACQUIRED ACTIVE IMMUNITY: person is directly exposed to the pathogen, develops a disease, survives, and therefore, acquires immunity ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY: person receives a vaccine

VACCINES… **A VACCINE consists of bacteria or viruses that have been weakened or killed so they a cannot cause a serious infection; or could include a toxoid or toxin that has been chemically altered to destroy its toxic effects -Includes antigens that stimulate a primary immune response but does not produce the severe symptoms of disease

KEY: PRODUCE MEMORY CELLS TO THAT ANTIGEN!

2) PASSIVE IMMUNITY ● Person receives antibodies produced by another individual ● Since the person does not produce the immune response themselves, this is short-term only (as long as the antibodies remain in the blood) ● The person remains vulnerable to the antigen if exposed at a later date  NO MEMORY CELLS

PASSIVE IMMUNITY: antibodies only NATURALLY ACQUIRED PASSIVE IMMUNITY: fetus acquires limited immunity from mother through placenta and/or breast milk (including colostrum)  ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY: person receives an injection of antiserum (antibodies) collected from a person who has already developed immunity against a particular disease

REVIEW QUESTION: Which of the following is naturally acquired active immunity? person got sick & got better person received a vaccination person received antibodies (serum) in an injection Fetus/baby received antibodies through placenta or in colostrum/breast milk

ORGAN TRANSPLANTATION and TISSUE REJECTION ● TISSUE REJECTION REACTION: when a transplant recipient’s immune system reacts against the donated tissue/organ immune system functioning normally Organ needed but isn’t “self” Small triangles are “self”; transplant could have “squares”

BONE MARROW STEM CELL TRANSPLANTATION and “SELF” TISSUE REJECTION ● TISSUE REJECTION REACTION: when a bone marrow stem cell recipient’s new immune system reacts against all “self” body cells immune system functioning normally Donated stem cells have given recipient the donor’s immune system

Only go through transplant if absolutely necessary. Donor will have bone marrow stem cells removed

Recipient will have their bone marrow cells destroyed by radiation Recipient will receive donated cells through an IV Stem cells will “seed” into bone marrow

● to minimize tissue rejection: Match donor and recipient tissues (“self” marker) Use immunosuppressive drugs (help with transplant acceptance, but may increase the recipient’s risk of infection)

ALLERGIC REACTIONS ● Excessive and misdirected immune responses that may damage tissue (abnormal response) ● Triggered by antigens known as ALLERGENS ● The immune system attacks a nonharmful substance, such as chocolate or pollen

ALLERGIC REACTIONS 1) Delayed-reaction allergy: results from repeated exposure of the skin to certain chemicals (e.g. household chemicals, cosmetics) -Activates T cells; T cells and macrophages collect in the skin and release chemicals that cause eruptions and inflammation (DERMATITIS) -“Delayed” because it takes about 48 hours to develop

ALLERGIC REACTIONS 2) Immediate-reaction allergy: An inborn ability to overproduce IgE antibodies in response to certain antigens/allergens (i.e. pollen, pet dander, etc.) Activates B-cells when 1st encountered & IgE antibodies attach to mast cells which contain histamine -Occurs within minutes of contact with allergen

Immediate-reaction allergy Subsequent (2nd +) exposure results in mast cells bursting and releasing allergy chemicals such as HISTAMINE Histamine causes blood vessels to dilate, tissues to swell, contraction of bronchial and intestinal smooth muscles, increased mucus production  The released chemicals cause allergy symptoms such as: hives, hay fever, asthma, eczema, or gastric disturbances

Extreme allergies… **Severe example of immediate-reaction allergy: ANAPHYLACTIC SHOCK! -Mast cells throughout the body release histamine -Severe drop in blood pressure (could lose consciousness and possibly die) -Person must receive an injection of epinephrine (adrenaline) to restore blood pressure

AUTOIMMUNITY / AUTOIMMUNE DISORDERS: ● Abnormal Function ● The immune system manufactures autoantibodies (antibodies that attack a person’s own body tissues) ● May result from a previous viral infection, faulty T cell development, or reaction to a nonself antigen that resembles a self antigen

Examples of Autoimmune disorders: Lupus erythematous: autoantibodies attack DNA (can affect whole body as result) Rheumatoid arthritis: autoantibodies attack cartilage of joints

Examples of Autoimmune disorders:  Insulin-dependent diabetes: T-cells cause destruction of insulin producing cells in pancreas

Examples of Autoimmune disorders: Multiple sclerosis: T-cells destroy myelin sheath around neurons

Examples of Autoimmune disorders: Grave’s disease- autoantibodies to thyroid stimulating receptor (overproduce thyroid stimulating hormone; involved in metabolism)

Examples of Autoimmune disorders: Crohn’s Disease: immune system attacks alimentary canal (leading to chronic inflammation)

IMMUNODEFICIENCY DISEASE Like autoimmune disorders, abnormal immune system function (compromised immune function) Ex: HIV Virus invades Helper T-cells, uses them to make more copies of the HIV virus, and then destroys the Helper T-cell Newly made viruses from destroyed Helper T-cell infects other Helper T-cells Without Helper T-cells, cannot activate Cytotoxic T-cells or B-cells  no immune system

HIV life cycle animation

REVIEW QUESTION: If a person has an inborn allergy, what happens the FIRST time they are exposed to the allergen? Histamine is released White blood cells move into the area B-cells produce antibodies that attach to mast cells A and B

REVIEW QUESTION: Why is anaphylactic shock so dangerous? Blood vessels constrict too much Blood pressure drops dramatically Blood pressure raises dramatically Oxygen cannot release from hemoglobin in RBC’s

REVIEW QUESTION: A person who had received a donated kidney may reject that kidney because Their immune system only recognizes their type of blood Their immune system cannot differentiate self from non-self. The receptors on the kidney cells are non-self The immune system cell receptors are non-self

REVIEW QUESTION: An autoimmune disorder is one where All immune cells have the wrong receptors B-cells have the wrong receptors T-cells have the wrong receptors One specific lymphocyte identifies a self receptor as non-self