Chapter 17

___________DEFENSES of the HOST:

THE IMMUNE RESPONSE

______________ ANTIBODY and LYMPHOCYTE

RESPONSE to an ANTIGEN

____________________

• Study of the defense mechanisms against infectious agents and foreign substances– Surveillance of the body– Recognition of foreign material– Destruction of foreign material

• Includes nonspecific and specific immunity– Nonspecific or _______: includes 1st and 2nd line of

defense

– Specific or ________: includes 3rd line of defense

• White blood cells (WBC) or leukocytes are play an important role

____________ IMMUNITIES - SPECIFIC

SUMMARY OF THE DIFFERENT ____________ IMMUNITIES

________ IMMUNE RESPONSEAdaptive Immunity

Third line of DefenseSpecific immunity is a complex interaction of

immune cells reacting against antigens• _________ RESPONSE

– First response to Ag– May take a week or more to develop

• __________ RESPONSE– Immune system remembers pathogen on subsequent

exposure– Immediate response

DIVIDED INTO 2 CATEGORIESHUMORAL IMMUNITY

-Eliminates _________cellular pathogensCELLULAR IMMUNITY

-Eliminates _______cellular pathogens

HUMORAL IMMUNITYproduction of specific _____________ against

foreign substances called antigens

PROPERTIES of __________• Substances that trigger _____ production or other

immune response: Antibody generator• Types : Proteins, polysaccharides- induce strong

immune response :Lipids, nucleic acids- weak response • Recognition of antigen directed at antigenic determinant or _______________-specific area on Ag against which Abs are formed

OVERVIEW of ________ IMMUNITY

• Mediated by B lymphocytes– a.k.a B cells

• Develops in bone marrow

• B cell receptors bind to Ag: triggers proliferation of B cells into– _________ cells

• produce antibodies

• antibodies produced when antigen binds to B cell receptor

– _________ cells

Extracellular Antigen

Proliferation & Differentiation of Activated B Cell

Plasma cell

Activates B cells that bind

Ag

Antibody Production

Ab + Ag

Memory cell

Helper T Cell

B Cell

Cellular Immunity

PROPERTIES OF _____________products of B Cell Activation

PROPERTIES of B CELLS:• Special group of

lymphocytes• Produced in bone marrow• Mature B cells migrate to

lymphoid organs• Produce: plasma cells

-produce Abs

memory cells

CLASSES of ANTIBODIES:1. IgG2. IgM3. IgA4. IgD5. IgE

• 80% of serum antibodies

• Also present in lymph, intestine, and tissue fluids

• Cross placenta– Protects fetus and newborn

• Fix complement

• Enhance phagocytosis

• Neutralize toxins & viruses

PROPERTIES of __ ANTIBODIES

PROPERTIES of

IgM ANTIBODIES• First Ab produced in

response to infection• Agglutinates microbes• 5-10% of serum

antibodies

PROPERTIES of IgA ANTIBODIES• Protection for

newborns• Mucosal protection• Present In secretions• 10-15% of serum Abs

PROPERTIES of IgD ANTIBODIES

• In lymph and on B cells• May act to delete defective B cells• Help initiate immune response• 0.2% of serum Abs

PROPERTIES of IgE ANTIBODIES

•On mast cells and basophils•Allergic reactions•Lysis of parasitic worms•0.002% of serum Abs

CLONAL SELECTIONthe proliferation of antigen-activated __ cells

(form secondary response to

antigen)(involved in antibody production)

CONSEQUENCES of ANTIBODY-ANTIGEN INTERACTIONS

1. ______________– Blocks adhesion of bacteria

and viruses to mucosa– Prevents toxin from interacting with

cell

2. Immobilization and prevention of adherence– Antibody bonding to cellular _______

to interfere with function

3. Agglutination and precipitation– Clumping of bacterial cells by

specific antibody• Bacteria more easily phagocytized

4. Opsonization– Coating of bacteria with antibody

to enhance _______________

5. ___________ (serum proteins involved with innate, non-specific immunity) – Antibody bonding triggers

classical pathway

6. Antibody-dependent cellular cytotoxicity– Multiple antibodies bind to a cell

which becomes target for certain nonspecific immune cells

CONSEQUENCES of ANTIBODY-ANTIGEN INTERACTIONS cont’d

RECOGNITION of SELF and NONSELF _____________

– Glycoprotein receptors located

on the surface of _______ cells– Role: recognition

• Confer specificity and _________ • Recognized by lymphocyte

cells as “self”• Lymphocytes recognize microbe

receptors as “nonself”– EX.: Major Histocompatability Complex

CLONAL ________________– The process of destroying B and T cells that react

to self as foreign Ags

CELL MEDIATED IMMUNITY• SPECIFIC CELLS

– T ________________• Respond to _____cellular antigens• Produce and respond to cytokines (chemical

messengers)• Subset of T cells with unique CD receptors

– Helper T cell/CD4– Cytotoxic T cell/CD8

• NONSPECIFIC CELLS– ANTIGEN PRESENTING CELLS

• ______________• ______________ cells

– NATURAL KILLER CELLS

SOME TYPES of T LYMPHOCYTES1. ________ T CELLS

– Regulate immune response to antigens by releasing cytokines (chemical messengers)

– Cytokines activate: • Other T cells, delayed type hypersensitivity)

• B cell production and differentiation• Macrophages

2. __________T CELLS– Bind and lyse cells (apoptosis)

• microbes, viral infected cells, foreign cells, cancer cells

– Mode of action • ___________ production• make lesions in the membrane of infected cells

• ___________– degrade proteins– Induce target cells to undergo apoptosis

ROLE of ____ T LYMPHOCYTES IN ANTIGEN RECOGNITION AND RESPONSE

• T lymphocytes have multiple copies of T cell receptors– Receptors have variable

sites for antigen bonding

• T cell receptors interact directly with “presented” antigen– T cell receptor does not

react with free antigen– Antigen must be

presented by an antigen presenting cell:

• B cells• Macrophages• Dendritic cells

ACTIVATION OF __________ T LYMPHOCYTES CELLS BY T

DEPENDENT AGS(CELL-MEDIATED CYTOTOXICITY)

NONSPECIFIC CELL MEDIATED IMMUNITY

• Activated ____________:

Macrophages stimulated by ingesting Ag or by cytokines• ________ Cells

Present antigens• Natural Killer Cells: Lymphocytes that destroy microbes, virus-infected cells, tumors

CELL COMMUNICATION IN IMMUNITY• Markers: the “eyes” and “ears” of the cell

– Cell surface ___________

• ________: the “voice” of the cell-chemical communicators– Small proteins released from human cells that

encounter foreign matter Two major classes of cytokines:

• _________ – important in control of viral infections• _________ – produced by leukocytes, important in innate

and adaptive immunity

• ___________ Molecules: the “hands” of the cell– Allow cells to adhere to each other– Recruit phagocytic cells to site of injury

SUMMARY OF MAJOR COMPONENTS OF ______________________