Immunology

Question 1

FasR (CD95)

Answer 1

Apoptosis of T cells (CD 4 and CD8)

Question 2

Primary signal of CD8 activation

Answer 2

TCR of naive T cell specific for Ag binds peptide on MHC I on DC.

Question 3

Secondary signal of CD8 response

Answer 3

B7 costimulatory molecule on APC binds to CD28 on T cell, then T cell becomes activated cytotoxic T cells (CTL)

Question 4

Colonal expansion of T cells

Answer 4

CD8 T cell secretes cytokines IL-2
CTLs also secrete perforins and granzymes

Then go to infected tissue

Question 5

Activated CD4 cells release

Answer 5

Th0

Question 6

Th0 can develop into the following Th cells:

Answer 6

Th1, Th2, Tfh

Question 7

Th0 (DC) cells activate into _______ in the presence of _______ and then activate Macrophages by expressing ________

Answer 7

Th1, IL12, CD40L to CD40 on MO and IFN-gamma to IFN-gammaR on MO causing MO to produce NO and oxygen radicals and TNF, IL-1

Intravesicular bacteria

Question 8

Th2 and Tfh activation

Answer 8

Soluble and extracellular Ag

DC ingested Ag presents in lymph on MHC II as peptide to activate naive T cells

B cells phagocytosis ECM Ag in lymph node and present peptide on MHC II

Question 9

Two signals for CD 4 activation from Th2 and Tfh in lymph node

Answer 9

In presence of IL-4 CD4 differentiates into Th2 or Tfh, which then bind to Ag presenting B cells

Th2 binds CD40L to CD40R on Bcell

Th2 secrete IL-4,IL-5 which induce B cell proliferation and differentiation into IgM plasma cells and somatic hyper mutation and isotope switching to IgE

Question 10

Tfh cells secrete _______ during Th0 activation

Answer 10

IL-21, IL-4, IFN-gamma

Tfh induces B cells to undergo isotype switching and somatic hypermutation to isotopes other than IgE

Question 11

Affinity Maturation

Answer 11

Colonial selection as Ag levels drop bc of Ag clearance,resulting in B cell survival with the highest Ag binding affinity and will have an isotype other than IgM (which are short lived plasma cells)

After activation, each B cell will have Ab with one specificity and one isotype expressed

Question 12

CD40R deficiency

Answer 12

Hyper-IgM syndrome

Lack of isotype switched Ab but abundance of IgM

Question 13

Toll-like receptors

Answer 13

Recognize structurally conserved molecules derived from microbes (PAMPs)

The TLR triggered determines what cytokines DC secrete

Question 14

Haptens

Answer 14

Non-immunogenic foreign substances that can react with an Ab on a B cell, trigger an immune response when coupled to a carrier protein

I.e. Urushiol –> poison ivy, reacts w skin proteins and forms hapten conjugates to induce an immune response

I.e. Conjugate vaccine

Question 15

Opsonization

Answer 15

Pathogen is marked for ingestion and is phagocytosed.

Question 16

Complement steps

Answer 16

Inflammation
Opsonization
Lysis of bacteria

Occurs in classical and alternative complement pathways

Question 17

Classical pathway triggered by

Answer 17

Binding of IgM or most IgG isotypes to a pathogen

Activated C1 acts on C2 and C4 and cleaves C4 into C4a and C4b

C3 convertase C4b2b cleaves C3 into C3a and C3b

Question 18

Best opsonin is:

best inflammatory one:

Answer 18

C3b

C5a

Question 19

MAC membrane attack complex:

Answer 19

C5b6-9

Question 20

Alternative pathway

Answer 20

More innate, can activate without Ab

C3b spontaneously cleared by C3, same MAC

Question 21

what are the two ways natural killer cells can Kill their target

Answer 21

1) via antibody dependent cellular cytotoxicity (ADCC) with the aid of antibodies

NK cell binds to IgGs Fc portion with its Fc receptor and NK secretes granzyme and perforins

2) natural killer cells can cause death and target cells that expressed a lack of an MHC 1 expression

Via KIR (killer inhibitory receptor) that recognizes MHC I

Question 22

What antibody process of Placenta during pregnancy

Answer 22

IgG, which protect the baby, and is present and the newborn immediately after birth known as passive immunity

Low count of antibodies between three and six months

IgM is produced in utero and has about 50% at birth

Question 23

Type I Hypersensitivity

Immune initiator
Ag type
Rxn Mechanism
Ex

Answer 23

Immediate

IgE and mast cells which release toxic mediators (usually the result of symptoms)

Soluble Ag

Mast cell activation

Allergic, asthma

Mechanism: sensitization (like Th2 response), activation (immediate, seconds and late, hours)

Skin test

Question 24

Type II Hypersensitivity

Immune initiator
Ag type
Rxn Mechanism
Ex

Answer 24

IgG

Cell mediated or matrix Ag

Complement (MAC), FcR cells (MO and NK cells)

Drug allergins

Foreign induced example: drugs, blood transfusion, graft rejection
Autoantigen induced example: myasthenia gravis, Graves’ disease, autoimmune hemolytic disease

Question 25

Type III Hypersensitivity

Immune initiator
Ag type
Rxn Mechanism
Ex

Answer 25

IgG

Soluble Ag

Complement, Phagocytes, Inflammation

Localized foreign Ag-induced example: Arthur’s rxn
Generalized foreign Ag-induced rxn: Serum sickness
Generalized autoAg induced: rheumatoid arthritis, lupus (butterfly rash)

Question 26

Type IV Hypersensitivity

Immune initiator
Ag type
Rxn Mechanism
Ex

Answer 26

Delayed type, 48-72hrs

Th1 and CTL (cytotoxic T cell lymphocytes)

Soluble Ag and cell associated Ag

MO and Cytotoxicity via CTL

Contact dermatitis and graft rejection

ForeignAg induced examples: poison ivy, PPD test, chronic allograft rejection

AutoAg induced Rxns example: type I diabetes, multiple sclerosis

Question 27

CTLA-4

Answer 27

Down regulates T cells (CD 4 and CD 8)