lymphatic system and immunity

antigens generate

antibodies

cell mediated immunity

destruction of antigens via T cells

especially effective against fungi, parasites, and viruses

antibody mediated (humoral) immunity

destruction of antigens by antibodies

works against antigens dissolved in body fluids and extracellular pathogens primarily bacteria

what triggers immune responses?

Specific portions of antigenic determinants (epitopes)

what self-antigens aid in the detection of pathogens?

major histocompatibility complex antigens (aka human leukocyte associated antigens)

exogenous antigen processing

antigen is processed and presented to immune cells by antigen presenting cells

endogenous antigen processing

foreign antigens are present inside infected body cells

APCs include:

macrophages, B cells, and dendritic cells

lymph trunks merge to form either

thoracic duct or right subclavian duct

what do lymph nodes contain

T cells, macrophages, dendritic cells, and B cells

outer cortex and inner medulla of a lymph node function as a _______

filter

White pulp of spleen consists of

mostly macrophages and lymphocytes

Within red pulp of the spleen…

• macrophages remove worn out or defective RBCs, WBCs, and platelets

• stores blood platelets

• production of blood during fetal life

lymphatic nodules

lymphatic tissue that are not surrounded by a capsule,and situated strategically to protect against foreign substances eg tonsils

Peyer’s patches

lymphatic nodules in the ileum of the small intestine

interferons

produced by virus infected cells to inhibit viral replication, has a role in suppressing cancerous tumors

macrophage migration inhibiting factor

prod by killer t cells; prevents macrophages from leaving site of infection

tumor necrosis factor (TNF)

prod by macrophages, stims accumulation of neutrophils and macrophages at site of inflammation

Cytokines

small protein hormones that stim or inhibit normal cell functions

Interleukin 1

• prod by macrophages

• promotes proliferation of helper t cells

• acts on hypothal to induce fever

IL-2

• Secreted by helper t cells

• costims proliferation of helper t cells, cytotoxic t cells, and B cells,

• activates NK cells

IL-4

• prod by helper T cells

• Costims for B cells

• causes plasma cells to secrete IgE antibodies

• promotes growth of T cells

IL-5

• prod by some T cells, most mast cells

• costim for B cells

• causes plasma cells to secrete IgA antibodies

IL-6

• Prod by helper T cells

• enhances B cell proliferation

• B cell differentiation into plasma cells

• secretion of antibodies by plasma cells

IgG

• Most abundant

• found in blood, lymph, and intestines

• cross from placenta to fetus (innate immunity)

IgA

• found in secretions: sweat, tears. saliva, mucus breast milk

• levels decrease during stress, lowering resistance to infection

• provides localized protection of mucous membranes against bacteria and viruses

IgM

• largest in size

• first antibody prod by primary response to antigen

IgD

• not well understood

• found mainly on surfaces of B cells as antigen receptors

IgE

• Most rare

• mediator of many common allergenic responses

• defends against parasitic infections

antibody actions

• neutralizing antigen

• immobilizing bacteria

• agglutination or precipitation

• activates compliment system

• enhanced phagocytosis

complement system is important against

bacterial infections

immune responses are…

much quicker and intense after the first exposure to an antigen

primary immune response

• b-cell differentiation occurs

• IgM antibody for a specific antigen is detected

• IgM response equal or slightly less follows

• immune system is primed

• memory cells may remain for decades

Secondary immune response

• more rapid

• larger amounts of antibody produced

• rapid response due to memory cells that do not have to differentiate

• IgM prod in similar quantities as primary, but IgG is prod in greater #s

self recognition

recognize own - Hajor histocompatability complex

self tolerance

they do not react to other self proteins

what leads to autoimmune diease

loss of self tolerance

positive selection develops

MHC

negative selection develops

self tolerance

self tolerance involves

anergy and deletion

Anergy

t cells alive but unresponsive to antigenic stimulation if there is no costimulation

deletion

death of T cells

Hypersensitivity reaction type I

IgE mediated rxn

examples of primary lympatic organs

• bone marrow

• thymus

largest mass of lymphatic tissue

spleen

examples of lymphatic nodules

• peyers patch

• tonsils

• Mucosa associated lymph tissue (MALTs)

what destoys antigens in cell mediated immunity

T cells

immunological surveillance is carried out by

cytotoxic T cells

hypersensitivity rxn 1

• IgE mediated rxn

• immediate

• Seasonal allergies, bee sting

hypersensitivity rxn II

• tissue specific rxn

• Immediate

• IgM, IgG

• Blood transfusion rxn, Graves disease, autoimmune hemolytic anemia

Hypersensitivity rxn III

• Immune complex mediated rxn

• Immediate

• IgA, IgM

• Systemic lupus erythematosus, rheumatoid arthritis

Hypersensitivity Rxn IV

• cell mediated rxn

• delayed

• none, uses lymphocytes and macrophages

• contact sensitivity to poison ivy and metals, tuberculosis test