1 Usmle - Immuno - Lymphocytes

Front 1

What genes code for MHC-I?

Back 1

HLA-A
HLA-B
HLA-C

Front 2

What cells express MHC-I?

Back 2

ALL nucleated cells
(not RBCs)

Front 3

MHC-I ANTIGEN LOADING

Back 3

Ag loaded in RER of mostly INTRACELLULAR PEPTIDES

Front 4

MHC-I binds w/ ________ to aid in transport to the cell surface.

Back 4

B2 microglobulin

Front 5

MHC-I mediates what kind of immunity?

Back 5

MHC-I mediates VIRAL immunity

Front 6

Genes for MHC-II?

Back 6

HLA-DP
HLA-DQ
HLA-DR

Front 7

What cells express MHC-II?

Back 7

ONLY APC's

Front 8

MHC-II binds TCR & _______.

Back 8

CD4

Front 9

MHC-I binds TCR & _______.

Back 9

CD8

Front 10

HLA subtype a/w HEMOCHROMATOSIS?

Back 10

A3

Front 11

HLA subtype a/w PAIR?

Back 11

*B27
PAIR =
Psoriasis
Ankylosing Spondylitis
IBD
Reiters Syndrome

Front 12

HLA subtype a/w GRAVES?

Back 12

B8

Front 13

HLA subtype a/w MS, Hay fever, SLE, & GOODPASTURE's?

Back 13

DR2

Front 14

HLA subtype a/w DM1?

Back 14

DR3

Front 15

HLA subtype a/w RA & DM1?

Back 15

DR4

Front 16

HLA subtype a/w PERNICIOUS ANEMIA --> B12 def & HASHIMOTO's THYROIDITIS?

Back 16

DR5

Front 17

HLA subtype a/w Steroid-responsive NEPHROTIC Synd?

Back 17

DR7

Front 18

NATURAL KILLER Cells

-- Function
-- Activation

Back 18

-- only LYMPHOCYTE of the INNATE immune system

-- Use PERFORIN & GRANZYMES
→ induce APOPTOSIS of VIRALLY infx cells & TUMOUR cells

-- Induced to kill when it senses an absence of MHC-I on a target cells

Front 19

NATURAL KILLER Cells

Activity enhanced by...

Back 19

IL-12

IFN-α

IFN-β

Front 20

What are the major functions of B cells?

Back 20

Make ANTIBODIES
● IgG
-- Opsonisation, neutralise viruses
-- HSR ② = Cytotoxic
-- HSR ③ = Immune complex
● IgG + IgM
-- Complement activation
● IgE
-- Mast cell sensitisation
-- HSR ① = Allergy

HYPER-ACUTE ORGAN REJECTION (Ab mediated)

Front 21

What are the major functions of T cells?

Back 21

-- CD4 T cells
-- -- help B cells make Ab &
-- -- produce IFN-GAMMA → MAC activation

-- CD8 T cells kill VIRUS infx cells directly

-- HSR ④ = Delayed Cell-mediated

-- ACUTE & CHRONIC ORGAN REJECTION

Front 22

T cell DIFFERENTIATION (handwritten)

Back 22

(handwritten)

Front 23

What are the 3 APC's?

Back 23

Macrophage
Dendritic cell
B cell

Front 24

Describe Helper T cell activation

Back 24

① APC phagocytoses foreign body → presents on MHC-II

② APC MHC-II interacts w/ CD4+Th TCR -- -- -- (signal ①)

③ APC B7 ligand interacts w/ Th CD28 -- -- -- (signal ②)

④ Th → cytokines

Front 25

Describe Cytotoxic T cell activation

Back 25

① MHC-I on virus infx cell (endogenous proteins) interacts w/ CD8+ Tc TCR

② IL-2 from CD4+Th1 interacts w/ Tc IL-2 receptor

Front 26

Describe B cell class switching

Back 26

① Helper T-cell activation
● RECEPTOR-mediated endocytosis of foreign Ag → presents on MHC-II
● Th MHC-II interacts w/CD4+Th TCR
● Costimulatory signal = B7 & CD28 (Th cell)

② Th2 CD40L interacts w/ B cell CD40 receptor -- -- -- (signal ①)

③ IL-4, IL-5, IL-6,IL-10 from CD4+Th2 -- -- -- (signal ②)

Front 27

Th1 cell

- Regulates _______immune response
- Secretes cytokines _______
- Activates ________
- Inhibited by ________

Back 27

- Regulates CELL-MEDIATED immune response

- Secretes cytokines: IL-2 & IFN-GAMMA

- Activates MACS & CD8 T cells

- Inhibited by IL-10 (from Th2)

Front 28

Th2 cell

- Regulates _______immune response
- Secretes cytokines _______
- Helps _____make _____
- Inhibited by ________

Back 28

- Regulates HUMORAL immune response

- Secretes cytokines: IL-4, IL-5, IL-6, IL-10

- Helps B cells make ANTIBODIES (IgE > IgG)

- Inhibited by IFN-GAMMA (from Th1)

Front 29

MACROPHAGE - LYMPHOCYTE INTERACTION

Back 29

Activated LYMPHOCYTES → IFN-GAMMA
&
Activated Mφ → IL-1 + TNF-α

STIMULATE one another

Front 30

Cytotoxic T cells have _____, which binds to MHC I on virus infected cells.

Back 30

CD8+

Front 31

CYTOTOXIC T cells release what?...& what does it do?

Back 31

Tc → cytotoxic GRANULES w/ PREFORMED PROTEINS:

① PERFORIN = helps deliver granule contents into target cell

② GRANZYME = serine protease → activates apoptosis

③ GRANULYSIN = antimicrobial → activates apoptosis

Front 32

What are 3 FUNCTIONS of ANTIBODIES?

Back 32

1.) OPSONISATION - promotes phagocytosis

2.) NEUTRALISATION - prevent bacterial adherence

3.) COMPLEMENT activation - MAC + C3b -- enhance opsonisation & lysis

Front 33

Structure of ANTIBODIES (handwritten)

Back 33

(handwritten)

Front 34

What are 5 features of the Fc portion of antibodies?

Back 34

5 C's:

★ CONSTANT

CARBOXY terminal

★ COMPLEMENT binding at CH2 -- (IgM & IgG only)

CARBOHYDRATE side chains

★ Confirms ISOTYPE = IgM, IgD etc

Front 35

What portion of the antibody determines the IDIOTYPE?

Back 35

Fab

IDIOTYPE = unique Ag-binding pocket
-- only 1 antigenic specificity expressed per B cell

Front 36

Name 4 ways antibody DIVERSITY is generated.

Back 36

1.) Random RECOMBINATION of VJ (L chain) or VDJ (H chain) GENES

2.) Addition of NTs to DNA during recombination
-- by TERMINAL DEOXY-NUCLEOTIDYL TRANSFERASE

3.) Random COMBINATION of L chains w/ H chains

4.) SOMATIC HYPER-MUTATION -- (following Ag stimulation)

Front 37

Describe ISOTYPE SWITCHING

Back 37

① MATURE B lymphocytes express IgM & IgD

② Differentiate → PLASMA cells by ISOTYPE SWITCHING =
-- ALTERNATIVE SPLICING of mRNA
-- mediated by CYTOKINES & CD40L

③ PLASMA cells secrete IgA, IgE, IgG

Front 38

Features of IgG

Back 38

[DOC NAP]
-- DELAYED (SECONDARY) response
-- OPSONISATION
-- fixes COMPLEMENT
-- NEUTRALISATION of bacterial TOXINS & VIRUSES
-- most ABUNDANT
-- ADCC - Ab Dependent Cell-mediated Cytotoxicity
-- crosses PLACENTA → infant PASSIVE immunity

Front 39

Features of IgA

Back 39

-- prevents ATTACHMENT to MUCOUS MEMBRANES
-- MONOMER in circulation
-- DIMER when secreted
-- TRANCYTOSIS - crosses EPITHELIAL cells
-- SECRETORY COMPONENT picked up from EPITHELIAL cells before secretion
-- SECRETIONS - tears, saliva, mucus, breast milk

Front 40

Features of IgM

Back 40

-- IMMEDIATE (PRIMARY) response
-- fixes COMPLEMENT
-- Ag RECEPTOR on B cell surface
-- MONOMER on B cell
-- PENTAMER shape → efficiently traps free Ag out of tissues

Front 41

Features of IgE

Back 41

[CLIME]
-- CROSS-LINKS on exposure to ALLERGEN → HSR ①
-- LOWEST conc. in serum
-- mediates HSR ① by...
-- -- -- releasing INFLAM MEDIATORS (eg HISTAMINE)
-- binds MAST cells & BASOPHILS
-- activates EOSINOPHILS -- WORM immunity

Front 42

What is found on the surface of B cells but has an unclear fxn?

Back 42

IgD

Front 43

Features of thymus-DEPENDENT antigens.

Back 43

-- PROTEIN component

-- B cell & Th2 CD40-CD40 &
-- IL-4, 5, 6, 10 from Th2
→ → →
-- CLASS SWITCHING &
-- MEMORY

Front 44

Features of thymus-INDEPENDENT antigens.

Back 44

-- LACK protein component
Eg.
-- LPS
-- Polysaccharide CAPSULES

→
-- can't present on MHC to T cell
-- NO memory

-- stimulate release of IgM ONLY