Immunology Lesson 1

ability of a host to resist a particular disease

Immunity

Anti-infective
other pathologies (allergy, auto-immunity, transplant rejection)

Different type of immune response

innate or nonspecific immunity

Unspecific mechanisms

acquired or specific immunity

specific mechanisms

present at birth
always present
unspecific
not enhance by previous exposure (no immune memory)
immediate response

Intrinsic defense mechanisms

previous contact with pathogen is required
specific recognition of the pathogen
imprimes on repeated exposure
immunologies memory

Specific or adaptative immunity

recognition ; activation ; response

different stages of adaptative immunity

Neutrophils (phagocytosis bacteria)
Basophils (allergy response)
Eosinophils (worms and fungi infection)

Granulocytes

hypersensitivities type I (Histamine and IgE)

Mast cells

Monocytes (macrophages ; dendritic cells)
T-Cells (helper ; cytotoxic)
B-cells (plasma cells)
Natural Cell Killers

Agranulocytes

Bone marrow
thymus
lymphocytes development and maturation

Primary lymphoid organs + role

where mature lymphocytes and antigens contact each other
spleen, MALT, Lymph nodes

Secondary lymphoid organs + role

defense against Ag in blood (LT/LB)

Spleen

circulating Ag from tissues with phagocyte cells

Lymph nodes

capture of Ag from gastrointestinal, urinary, reproductive tracts

mucosal associated lymphoid tissue (MALT)

Substances that are recognize as foreign and trigger an immune responses

Ag (Def)

Immunogenicity -> ability to trigger an immune response
Antigenicity -> ability to react specifically with products to an immune response (Ab)
(Ab bind and inactivate a specific Ag)

Properties of Ag

inherited as a part of the innate structure (1st of line of defense)
biological -> normal flora, microbial
chemical -> acidic ph, stomach, vagina ; lysozyme of saliva and tear
physical -> skin, mucosal membrane

Host defense mechanisms - Natural barriers

natural, non specific ; second line of defenses

immune defenses : innate

acquired specific ; third line of defenses

immune defenses : adaptative

inflammation, activation of complement, phagocytosis, activation of NK cells, cytokines

innate immunity

reaction to any traumatic event in any tissues

Inflammation response (def)

rubor, heat, tumor, dolor

4 classic signs of inflammation

to mobilize and attract immune components to the site of the injury
to activate mechanisms to repair tissue damage and localize and Clea away harmful substances
To destroy microbes and block their further invasion

main function of inflammation

Initiation ; vascular reaction ; edema and pus formation ; resolution-scar formation

Acute inflammation 4 steps

occurs when the presence of a MO or foreign molecules or tissue damaged is detected

Acute inflammation -Initiation

tissular response
expansion of capillaries to increase blood pressure, blood flow
increase permeability of the microvasculalure

Acute inflammation - vascular reaction

leukocytes and extravasation
neutrophils recruitment (chemotaxis)
opsonization and phagocytosis

Acute inflammation -Edema and pus formation

release of chemical mediators

Acute inflammation -Resolution-scar formation

attraction -> rolling -> margination -> diapedesis -> migration -> chemotaxis -> opsonization -> phagocytosis and cell lysis

The leukocytes reach the damaged tissue attracted by the chemotactic factors and they are activated by the cytokine

edema and pus formation

pathogens are covered by pre-existing Ab or proteins of complement system (C3b)

opsonization

refers to a protein that binds to the bacterial wall and prepare the pathogen to be destroyed by other components of the IS
ex opsonin : natural : Ab ; proteins CS

opsonin

a yellowish or greenish opaque liquid produced in infected tissus, consisting of dead white blood cells (leukocytes), and bacteria with tissue debris and serum

Pus

damaged cells are replaced

resolution-scar formation