MMSC415 Exam 1 Study Material - Key Terms and Definitions in Immunology

immunology

study of physiological mechanisms of humans used to defend body from invasion by microorganisms

CD4 T cells are MHC-II restricted and helpers, CD8 T cells are MHC-I restricted and cytotoxic

compare CD4 T cells with CD8 T cells

immunity

Resistance to disease

innate immunity

nonspecific, can be inducible or non-inducible, natural barriers and the inflammatory response (phagocytosis, inflammation, complement proteins)

1st is external, like skin and mucosa.

2nd is internal, including WBCs and inflammation.

3rd is adaptive responses, and having the memory to recall a pathogen the body has seen before

differentiate bw the 1st, 2nd, and 3rd (acquired) lines of defense

Specificity of Immune Response

Involves recognition, activation and response

may be natural (innate) or acquired (adaptive)

Memory immune response

recognizes and mounts even stronger attacks on previously encountered pathogens

Recognition (immune response)

sense of self and non-self (ability to know body's natural microbiome vs pathogens, failure in this aids in autoimmune disease)

adaptive immunity

the ability to recognize and remember specific antigens and mount an attack on them (either humoral or cell mediated)

Humoral mediated immunity (HMI)

main defense against extracellular pathogens

cell mediated immunity (CMI)

main defense against intracellular pathogens, usually direct cell-to-cell contact or production of cytokines

monocyte

3-10% of WBCs in periph blood, give rise to macrophages, agranulocytes

macrophage

large phagocyte found in lymph nodes and other tissues of the body

ex: Kupffer cells (liver), alveolar, microglial; die by apoptosis

granulocyte

a white blood cell that contains multiple small granules in its cytoplasm

neutrophil

40-75% of WBCs in periph blood, granulocytic and phagocytic leukocyte formed in bone marrow. aka PMNs

eosinophil

white blood cell containing granules that stain red; associated with allergic reactions

NK cell

3% of periph WBCs, large and granular, mediate rapid lysis of virus-infected, tumor, and foreign graft cellcells

chemotaxis

movement by a cell or organism in reaction to a chemical stimulus

opsonin

an antibody or other substance that binds to foreign microorganisms or cells, making them more susceptible to phagocytosis.

defensin

A type of protein made by phagocytes that kills bacteria and enveloped viruses by insertion into their plasma membranes.

oxidative burst

oxygen-dependent, reactive oxygen molecules (O2-, H2O2, OH-) increase during phagocytosis to better enable phagocytes

hygeine hypothesis

suggests that limiting exposure to pathogens may lower immune tolerance and the ability to cope with harmless antigens

Pattern Recognition Receptors (PRRs)

cell proteins able to recognize specific molecular patterns

Toll-like receptors (TLRs)

-A type of PRR

-Recognize PAMPs

-Set in motion a cascade of events inside the cell that amplifies and orchestrates a defense response to the pathogen

mast cells

present in connective tissue (esp blood vessels and nerves), promote inflammation, granules w heparin and histamine. associated w type 1 (IgE) hypersensitivity rxns (allergic)

Extravasation

interactions bw PMNs and endothelial cells (selectins, integrins). also transendothelial migration aka diapedesis

oxygen-independent killing

defensins, proteases, hydrolases

heat, pain, swelling, redness

4 cardinal signs of inflammation

C-reactive protein (CRP)

member of pentraxin family. early indicator of acute inflammation, but nonspecific. can detect within 6-12 hours after injury.

elevated in autoimmune disease, transplant rejection, malignant disease, heart attack

erythrocyte sedimentation rate (ESR)

a nonspecific blood test to measure how quickly erythrocytes settle at the bottom of a test tube containing a blood sample - measure of inflammation

the most important, aka the heart of all 3 pathways

C3 in the complement cascade

C5b6789

what's the alphanumerical code for the membrane attack complex?

complement fixation

uses virus-specific antigen, and reaction between antibody and antigen cause fixation of the complement, resulting in membrane lysis

increasing vasodilation and permeability

C2b, C3a, and C5a are known for

chemotaxis (neutrophils and monocytes)

C5a alone is known for

anaphylaxis (inflammation, degranulating mast cells and basophils)

C3a, C4a, C5a are known for

Ab-Ag complexes OR crp

what is the classical pathway activated by?

C1, C2, C4

what are the unique components of the classical pathway

2 IgG or 1 IgM

what does the classical pathway require in terms of recognition

contact w foreign substance, not Ab dependent (diff from classical)

what is the alternative pathway activated by?

Factor B, Factor D, Properdin

what are the unique components of the alternative pathway

IgA dimer binds to antigen, allowing for a quicker response than classical

what does the alternative pathway require in terms of recognition

Zymogen

protein secreted in an inactive form and activated by cleavage

feed-forward mechanism of complement activation, where C3 is fed back and forth bw classical and alternative bc both need C3b

explain the amplification loop

independent of antibody, instead lectin binds to mannose-containing carbs of bacteria, fungi, protozoa, viruses. interact with two proteases and make MASPs

explain the MBL pathway

immunogen (remember, all immunogens are antigens)

substance capable of producing immune response

antigen

substance that has ability to interact with BCR, TCR, or Ab

hapten

elicits immune response only when attached to a carrier (too small to be immunogenic alone)

epitope

an antigenic determinant; the particular chemical group or groups in a macromolecule (antigen) to which a given antibody binds.

agretope

region of processed Ag that binds to MHC molecule

valence

# of epitopes / molecule

antigenicity

capacity of Ag or hapten to bind to Ab, TCR, or BCR, specific reactivity!!!

immunogenicity

inherent ability of a substance (immunogen) to stimulate immune response, form antibodies, and activate lymphocytes (like T cells)

heterologous antigens

related antigens from another species

paratope

antigen binding site on the antibody

antibody (immunoglobulin)

protein produced by B cells that protects against substances that are potentially harmful to the body

allotype

the types of antibodies found within one species

idiotype

the types of antibodies found within one individual

isotype

The types of antibodies found in all different individuals in related species

hybridoma

a cell hybrid produced by the fusion of Bcells (plasma) with myeloma cells

electrophoretic separation

many Abs are isolated in gamma globulin part of the serum during what process

4 polypeptide chains in shape of Y

what does the monomer structure of immunoglobulin look like

IgG antibodies

- 75% of serum Ab

- activates complement (Ig__3 is more effective than 2, than 1.. 4 doesn't activate

-C1q MUST CROSSLINK 2 or more of these

- crosses placenta at birth (moms give high levels to babies)

- neutralizes pathogens so no longer infectious

IgM antibodies

- 5-10% of serum Ab

- pentamer (i.e. 10 binding sites)

- v large, so confined to intravascular spaces

- first antibody produced after antigenic exposure

IgA antibodies

- 10-15% of total serum Ab

- the predominant antibody in secretions (tears, milk, intestinal/genital fluids)

- secretory component: tethers it to mucus and protects against proteolytic enzymes

IgD antibodies

- 0.2% of serum Ab

- found on surface of B lymphocytes as BCRs

- functions in activation of B cells

IgE antibodies

- trace amts in serum Ab

- mast cells, basophils, activated eosinophils all have high affinity receptors for this

- potent activator of allergic reactions

noncovalent

what kind of bonds form between Ags and Abs?

hydrogen bonds

noncovalent attraction bw hydrogen and electronegative N O or F

electrostatic forces

opposite charges attract, like Na+ and Cl-

van der Waals forces

(+) or (-) charged regions of a polar molecule attract each other

hydrophobic bonds

association of hydrophobic groups

affinity

strength of a single Ag-Ab interaction, determined by sum of noncovalent attractive forces

avidity

strength with which a multivalent Ab binds to a multivalent Ag

avidity, affinity

IgM has a greater ______ than IgG, but IgG has a greater ______ than IgM

monoclonal antibodies (mAbs)

identical laboratory-made antibodies produced by plasma cell clones

major histocompatibility complex (MHC)

Group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances.

MHC restriction

the property that a given T-cell receptor recognizes its peptide antigen only when the peptide is bound to a particular form of MHC molecule.

cytokine

small proteins/peptides secreted by cells that act to change the behavior of other cells, bind to specific receptors on target cells

interleukin

- A chemical secreted by a T cell (usually the helper Ts) that stimulates activation and proliferation of other immune system cells.

- basically secreted by WBCs to stimulate other WBCs

interferon

Protein produced by cells in response to being infected by a virus; helps other cells resist the virus by interfering with viral replication

monokine

a cytokine released by a monocyte (macrophage).

lymphokine

a cytokine released by a lymphocyte.

anergy

absence of the normal immune response to a particular antigen or allergen

human leukocyte antigen (HLA)

aka MHC for humans, genes that code for proteins found on cell surfaces that help immune system recognize foreign substances

anamnestic response

upon second encounter with same pathogen immune system mounts a faster and more intense response

recovery from infection

give an example of natural active immunity

vaccine

give an example of artificial active immunity

IgG in placenta, IgA in breast milk

give an example of natural passive immunity

IVIG

give an example of artificial passive immunity

bone marrow and thymus

what are the main primary lymphoid tissues

lymph nodes and spleen

what are the main secondary lymphoid tissues

originate in the bone marrow, head to spleen for maturation where they go thru somatic recombination to determine specificity, then mature b cells go to blood stream then lymph nodes, then to another secondary tissue

explain the cycle of B cells (where they originate, where they go, how they mature, etc)

originate in the bone marrow, travel to the thymus for maturation and become T cell receptors, enter blood ad go to lymph notes, then other secondary tissues

explain the cycle of T cells (where they originate, where they go, how they mature, etc)

b cells have a chance to alter themselves, t cells don't

what's the difference between how B and T cells mature, other than the location?

MALT (mucosa-associated lymphoid tissue)

- the collection of lymphoid tissues that protect the epithelia of the digestive, respiratory, urinary, and reproductive systems

- similar to lymph node, just not encapsulated

Gut-associated lymphoid tissue (GALT)

- A collection of lymphoid tissue in the gastrointestinal tract that includes the appendix, the lacteals, and Peyer's patches.

M cells

members of GALT, filter and funnel antigens into lymphoid tissues

somatic recombination

how do b cells determine their specificity

MHC-I

- on all nucleated genes, bind antigens synthesized within cells (intracellular, endogenous!!!)

- present antigens to CD8+, cytotoxic T cells, and NK cells