Inflammation and Immunity.part 1

8/7/2019 Inflammation and Immunity.part 1

http://slidepdf.com/reader/full/inflammation-and-immunitypart-1 1/22

Immunology

Immunology

Useful activities of the immune system Defense against invading pathogens

(activated in response to an antigen or

immunogen)

Removal of aged ³worn out´ cells andtissue debris-wound healing and

inflammation

Immune surveillance-identification and

destruction of abnormal or mutant cells

(i.e. cancer or virally inf ected cells)



Immunology

Not useful and /or harmful activities of the immune

system

Inappropriate responses-allergies andautoimmune diseases

Tissue rejection



Immunology

Two separate but interdependent components of

the immune system

Innate

Adaptive



Eff ector Cells of the Immune System


Leukocytes (Innate Immunity)

Neutrophils, Eosinophils, Basophils

Monocytes (Macr ophages)




Dendritic Cells (Adaptive Immunity)

specialized antigen presenting cells (APCs) : tissue

sentinels that carry processed pathogenic material to

the lymph system




Lymphocytes (Adaptive Immunity) T cells (cell mediated immunity)

B cells (humoral immunity)




Lymphoid system and Lymphocyte circulation

Thymus

Lymph nodes and spleen





Innate ImmunityInnate Immunity

Innate Immunity: cells with germ line±encoded

proteins to recognize pathogens (ancient system)

First line of defense-nonspecific

Keeps infection limited Recruits cells of the adaptive immune system



Innate Immunity Innate Immunity

Most active at interface between the environment and epithelial surfaces (skin, GI, GU, and sinopulmonary

tracts)

Mucus

Traps pathogens

Contains IgG and IgA, complement proteins, lectins,

monocytes/macrophages



Innate Immunity

Host cells of the innate immune system sense³danger signals" through PRRs (pattern recognitionreceptors, i.e., C-reactive protein, toll-like receptors, lectins,serum amyloid protein) that:

recognize PAMPs (pathogen associated molecular patterns), the common molecular structures shared by many pathogens

recognize host cell molecules produced in responseto infection such as heat shock proteins and fragments of the extracellular matrix



{ Innate Immunity, cont.}

Recognition leads to

activation/production of the complement

cascade, cytokines, and antimicrobial

peptides as effector molecules

activate dendritic cells to mature and to

express molecules on the dendritic cell

surface that optimize antigen presentation (a process we¶ll talk about later) to respond to

foreign antigens.




Example of PRR: Toll-like receptors (TLRs)

Plasma membrane proteins on host cells that recognizeand bind with pathogen markers (PAMPs)

Allow effector cells of immune system to recognize

pathogen as ³not self´

Signals effector cells to engulf and phagocytize pathogen

Induces the effector cells to release chemicals that: contribute to inflammatory process

recruit cells of the adaptive immune process





Components of Innate ImmunityComponents of Innate Immunity

Inflammation (redness, warmth, swelling, pain)

Interferon (proteins that defend against virusesnonspecifically)

Natural Killer Cells (specialized lymphocytes that nonspecifically lyse virally infected and/or cancerous host cells)

Complement System (a group of inactive circulating proteins,that when activated sequentially, destroy the plasmamembrane of the pathogen)




Inflammation

� Redness, warmth, swelling, pain and loss of

function

� Redness, warmth, swelling, pain and loss of

function



Normal Vascularized Tissue

Anatomy

Normal Vascularized Tissue

Anatomy

� Capillaries and post-capillary venules

� Capillaries

± short, 1-2 mm tubes formed of a single layer

of flattened endothelial cells supported on a

basement membrane

± basement membrane:collagen fiber bundlesembedded in a gel of proteoglycans



Normal Vascularized TissueNormal Vascularized Tissue

� Vascular permeability is determined by the

endothelial cells of the capillary wall

� Adjacent endothelial cells form junctions

� Most substances that cross between the

capillary and the tissue must cross through

the endothelial cell by way of diffusion or in

transfer vesicles



Normal Vascularized TissueNormal Vascularized Tissue

� Surrounding thevessels is theextracellular matrix-proteoglycans

± anchorage for collagen andelastic fibers

± fibroblasts

± macrophages

± mast cells� Formation of tissue

fluid governed byStarling forces



Acute Inflammation Acute Inflammation

� Vascular component

± Increased blood flow to damaged tissue

± Increased capillary and venule

permeability

� Cellular component

± Large numbers of specialized leukocytes

move to tissue spaces� Formation of exudate



Inflammation (Vascular component)Inflammation (Vascular component)

± Localized vasodilationinduced by histaminereleased from mast cellsin damaged tissue(hyperemia thus war mth

and heat)

± Increased capillarypermeability by enlargingcapillary pores (allowsplasma proteins[complement and kininsystems and fibrin],WBCs and lymphocytesto area)




Inflammation (Vascular component)Inflammation (Vascular component)

± Localized edema (dueto increased blood flowand increased capillarypermeability thusproteins in tissue)(tissue swelling)

± Pain due to localdistention of tissue andstimulation of afferentneurons in damagedregion

Documents

Inflammation and Immunity.part 1