Immunology

Question 1

What are the functions of complements?

Answer 1

Complements are proteins that:

a) Activate inflammatory pathways
b) Recruit phagocytes
c) Opsonisation of pathogens
d) Remove immune complexes
e) Lysis of certain pathogens, such as through MAC formation

Question 2

What are cytokines?

Answer 2

Cytokines are small proteins released by cells:

a) signalling molecules which induce response by binding to receptor
b) can have effect on cell behaviour that releases cytokines

Question 3

Name the atypical TB condition named MAC. What is the CD4 count when infected with this condition?

Answer 3

Mycobacterium Avium Complex infection. When CD4 count is less than 100

Question 4

Define primary and secondary prophylaxis

Answer 4

Primary prophylaxis: Measures to avoid first occurence of infections
Secondary prophylaxis: Measures to maintain treatment and prevent recurrence of infection

Question 5

How are macrophages and monocytes related to each other?

Answer 5

Blood monocytes will mature into macrophages upon entering tissues.

Question 6

What are macrophages and monocytes known as collectively?

Answer 6

Mononuclear phagocytes

Question 7

Which complement receptor is found on erythrocytes?

What is the function of this receptor?

Answer 7

CR1.

Binds to soluble immune complexes coated with C3b for transport to spleen.

Question 8

What are the 3 types of complement receptors?

Answer 8

1. Receptors on phagocytic cells: CR1, CR3, CR4: Recognises C3b bound on bacteria
2. Receptors on erythrocytes: CR1: Binds to soluble immune complexes coated with C3b for transport to spleen
3. Receptors on B cells: CR1, CR2: Recognises C3b breakdown products in association with antigens (CR2 is part of the B cell co-receptor complex)

Question 9

What are the effects that can be elicited by C3a and C5a?

Answer 9

Can cause inflammation and phagocyte recruitment

Question 10

C5 - C9 deficiency leads to?

Answer 10

Recurrent Meningococcal infection

Question 11

MHC I is involved in infections that occur inside/outside the cell? How about MHC II?

Answer 11

MHC I is involved in infections that occur inside the cell.

MHC II is involved in infections outside the cell.

Question 12

What is the effect of CD59 on MAC formation?

Answer 12

CD59 prevents the final assembly of MAC at the C8 to C9 stage.

Question 13

What condition is observed from mutation of Factor H?

Answer 13

Age-related macular degeneration

Question 14

Name the condition resulting from deficiency of C1 inhibitor

Answer 14

Hereditary Angioedema (No urticaria, usually asymptomatic until puberty)

Question 15

What do red cells lack in Paroxysmal Nocturnal Haemaglobinuria? What is the consequence?

Answer 15

CD55 and CD59. Red cells become susceptible to complement lysis.

Question 16

What condition results from C5 - C9 complement deficiency?

Answer 16

Recurrent Meningococcal infection

Question 17

What condition results form C3 complement deficiency?

Answer 17

Recurrent pyogenic infections

Question 18

Most T cell development takes place in the cortex or medulla?

Answer 18

Cortex

Question 19

What type of T cells does thymic medulla only contains?

Answer 19

Mature single-positive T cells

Question 20

Where were MHC Class I molecules synthesised in? What molecule do they bind to after synthesis?

Answer 20

ER lumen. Binds to TAP

Question 21

In T cell development, which one occurs first: double negative or double positive?

Answer 21

Double negative first

Question 22

Which region of T Cell Receptor binds to antigen?

Answer 22

CDR3 region of T cell receptor

Question 23

What are TAP 1 and 2 involved in?

Answer 23

TAP1/2 are transporters associated with antigen processing. They help transport peptide antigen to ER lumen.

Question 24

Where are the invasions leading to MHC I or MHC II activation?

Answer 24

MHC I activation: when there is something wrong inside the cell.
MHC II activation: when there is something wrong outside the cell.

Question 25

Which MHC molecule is bounded by invariant chain initially?

Answer 25

MHC II

Question 26

How many signals are there in T cell activation. Elaborate on what happens in each signal.

Answer 26

2 signals in T cell activation.
1st signal: TCR + CD4/CD8 with MHC + peptide Ag
2nd signal: Must be from the same cell. CD28 and CD80/86 upregulated in the presence of danger signals