MicroBIO-Immunology – Flashcards

A Skin

B Neurons

C Blood

D Liver

- Self Renewal

- Potency

- Exist in small numbers

- Relies on cell surface markers for identification

T Cells

B Cells

NK Cells

-Dendritic Cells

-Monocytes/Macrophages

-Granulocytes (neutrophils, eosinophils, and basophils)

-Mast Cells

T Cell

B Cell

NK Cell

Immature Dendritic Cell

Macrophage

Granulocytes (neutrophils, basophils, eosinophil, mast cell, monocytes)

Which cells are components of innate immune defense?

How soon after infection is the innate immune response triggered?

1. Recognition of infected cells

2. Release of perforins and granzymes

3. Induction of cell death "apoptosis"

1. in the liver

2. in the lungs

3. in connective tissues

4. in the bones

5. in the kidney

6. in the brain

Major function: to engulf and digest cellular debris and pathogens= phagocytosis

-processing and presentation of antigens to T-Lymphoctyes

Neutrophils: -Predominant in acute inflammation

- 50-70% of circulating whitle blood cells

Eosinophils: -Associated with allergic inflammation and parasitic infection

- found predominantly in tissues rather than bloodstream

Basophils: -Associated with anaphylactic allergy

-found in blood or in tissues (as Mast Cells)

1. Bind to a specific cell-surface receptor & then signaling takes place, which alters cell functions:

-increasing the # of surface receptors for other molecules

- suppressing their own effect by feedback inhibition

- results in production of other cytokines

2. cytokines can share similar functions: Redundant

3. Are pleiotopic- diff. cell types to secrete the same cytokine or for single cytokine to act on several diff. cell types

4. act synergistically (two or more cytokines acting together) or anagonistically (causing opposing activities)

Autocrine- if the cytokine acts on the cell that secretes it

Paracrine- if the cytokine acts on closed neighbor cell

Endocrine- if the cytokine diffuses to distant regions of the body (carried by blood)

Pathogen Associated Molecular Pattern

Pattern Recognition Receptor

B1. Toll-like Receptor (TLR)

B2. Nod Like-Receptor (NLR)

B3. Macrohpage-Mannose Recepor (MMR)

-Membrane Associated receptor

-Expressed on surface

-Expressed inside cell/vacoules

-cyosolic receptors

-Not expressed on the surface

-Expressed inside cell/free in the cytoplasm

-Mannose-rich glycans are short carbohydrate chains with the sugar mannose or fructose as the terminal sugar

-They are commonly found in microbial glycoproteins and glycolipids but are rare in those humans

After phagocytosis, macrophages and dendritic cells can

participate in antigen presentation, in which the phagocyte

moves parts of the ingested material back to its surface

1. Destroy invading pathogens and any toxic molecules they produce

2. Highly specific to the particular pathogen that induced them

3. The innate responses call the adaptive immunce responses into play,and they both work together to  eliminate the pathogens

4. Provide long-lasting protection. A person who recovers from measles, for ex. is protected for life against measles by the adaptive immune system

5. The ability to distinguish forgeign from self is afundamental feature of the adaptive immune system

Senses pathogens by recognition of PAMPs

Cytotoxicity- Kills infected cells

Phagocytosis- Kills pathogens directly

1. T-cells develop in the bone marrow and migrate to thymus

2. Positive selection- T cells that can interact with MHC

3. Negative Selection- T cells that can interact with MHC with only low avidity(entusiasm)

4. Maturation and seeding in the lymphoid system

5. Binding of pathogenic peptides to MHC leads to high-avidity interactions with the TCR and results in T-cell activiation

1. Exogenous Antigens

MHC II

2. Endogenous Antigens

Foreign antigens that are generated within the cell because of viral or intracellular bacterial infection

MHC I

-All cells express MHC I because if virus infects cell can alert  CD8 T cells to kill infected cell

-MHC II only expressed by innate cells that are able to phagocytose pathogen and present it on MHC II which binds to TCR on CD4 T cells= Helper T cells

- The V region of the TCR a(alpha) and b(beta) regions 

- highly variable from one t-cell clone to the next

-reflecting their role in antigen presentation

-recognize peptide fragments presented with MHC I and MHC II molecules found on APCs or target cells

Co-receptor CD4 and CD8 allows prolonged engagement between the antigen presenting cell and the T cell

T_h- which expresses CD4 glycoproteins on their surfaces

T_c- which expresses CD8 glycoproteins on their surfaces

(therefore, acquired immunity is composed of activated CD4(T_h) and CD8(T_c) cellular responses)

Naive Cells-  are cells that have matured, in the central lymphoid organ, have entered the lymphatic system, but that have yet to encounter their cognate antigen

Effector Cells- are cells that have been activated by their cognate antigen, and are actively involved in eliminating a pathogen

Memory Cells- are long-lived survivors of past infections

1. progenitor T Cells leave the bone marrow and enter the thymus

2. After arriving at the thymus, these cells enter the outer cortex and begin to proliferate slowly

3. During 3wks of development in the thymus, the differentiating T-Cells progress through a series of stages marked by the changes in their cell surface phenotype

ONE T cell = SEVERAL copies of same TCR

ONE clone of T cells = ONE specificity for TCR

ONE thymus = LIMITLESS clones of T cells

ONE thymus = LIMITLESS specificity of TCR

ANTIGEN = IMMUNOGEN

  Large foreign molecules that can elicit an immune response 

-Proteins and polysaccharides are more immunogenic than lipids and nucleic acids

-Antigens from individuals of same species are less immunogenic than those from distant species

Immunologically active portion of the antigen 

Immunogenicity-The ability of an antigen

to induce an

Immune Response

Antigenicity-The ability of an antigen

to bind specifically

to an Antibody

Antigens must be degraded into small peptides and bound to protein called MHC proteins

They are specialized for the presentation of intracelluar antigens to the TCR of CD8+ T-Cells

(Endogenous Peptides)

They are specialized for the presentation of extracellular antigens to the TCR of CD4+ T-Cells  

(Exogenous Peptides)

Specialized cells = Antigen Presenting Cells (APC)

1. Present endogenously derived peptides

2. Peptide (antigen) can be either self-derived or derived from viruses

3. Because MHC class I is present on all cells, any cell can interact with T-Cells if infected by a virus

1. Present exogenous antigens

2. Antigen has been phagocytosed and processed, ex. bacteria

3. This is performed by professional antigen-presenting cells. ex. macrophages

IgG

IgA

IgM

IgD

IgE

Paratopes

Epitopes

Antigenic Determinants are in variable regions, and they both have millions of different specificities

Ig- Form is free or surface bound

-No antigen presentation by MHC

-Free Antigens

-No Antigen Processing

TCR- Form is ONLY surface bound

-Antigen presentation by MHC

-Antigen processing required

Immobilization & Prevention of Adherence

 (won't let bacteria Adhere)

Toxin Neutralization

(the toxin will damage the cell so IgG will neutralize it)

1. Agglutination

2. Precipitation

                            - immunoglobulin selection of B Cell

Diversity

Diversity of antibodies (and TCR in T cells) 

Transition from membrane-bound Ig

to secreted Ig is Called

“Class Switching

B Lymphocytes

Development: Self/Non-Self Seletion

-Ig Diversity

-No MHC restriction

Activation: Recognition of free antigens

Proliferation:

Differentiation: Plasma B Cells

-Class Switching

Memory

T Lymphocytes

Development: Self/Non-Self Seletion

-TCR Diversity

-MHC restriction

Activation: Recognition of MHC-Peptides

Proliferation:

Differentiation: Th & Tc Cells

-No Class Switching

Memory

Specificity

of Innate and Adaptive Immune Response

Diversity

of Innate and Adaptive Immune Response

Discrimination of self from non-self

of Innate and Adaptive Immune Response

Memory

of Innate and Adaptive Immune Response

: Disorder in which cells of the immune system are missing (B and T Cell)

Increased susceptibility to INFECTIONs 

Full Blood Count

Antibodies against surface markers of immune cells (T cells = CD4, CD8, CD3, TCR 

B cells = BCR (IgM, IgD), MHC class II)

Genetic Factor= Primary Immunodeficiency Lymphocyte Deficiencies 

Antibody Deficiencies 

Phagocyte Disorders

Innate Immunity Deficiencies

                      SCID = Severe Combined

                            ImmunoDeficiency

                             MHC class II deficiency

                             CD3γ deficiency

                                CD8 deficiency 

External Factor= Acquired Immunodeficiency

                                Chemotherapy

                               Drug treatment 

                               Other diseases

                                      AIDS =

Acquired ImmunoDeficiency

Syndrome

SCID is due to mutations in γc gene leading to lack of T and B cells

HIV infects and destroy CD4+ T cells and as result of killing so many CD4+ T cells Immunity is lost

CD4+T cells are very important in cellular immunity

The failure of an organism to recognize its own constituent   parts as SELF which results in an immune response against its own cells and tissues*** Do REACT to SELF***

Systemic Autoimmunity(effects the nervous system)- Immune system attacks

different organs of the body

-Systemic Lupus Erythematosis

                         -Rheumatoid Arthritis

                         - Systemic Sclerosis Dermatomyositis

Autoantibodies directed against contents of the cell nucleus

Organ-specific Autoimmunity-Immune system affects only one organ or tissue type

-Diabetes mellitus type 1 (Pancreas)

                  -Hashimoto's thyroiditis (Thyroid gland)

                  -Multiple sclerosis (Brain)

                  -Myasthenia gravis (Muscles)

Autoreactive T cells with

a TCR specific to myelin components

In Autoreactivity- CD8 recognizes cells represented by B Cells -need a MHC-I  (class I)

In Cytotoxicity- B-cell is dead