Immunology Lecture 5_Cytokines and Complement Pathway

Question 1

Are cytokines stored as preformes molecules or made on demand?

Answer 1

Made on demand

Question 2

How do cytokines regulate the differentiation of hematopoitic cells?

Answer 2

By activating signal transduction pathways (JAK/STAT) that result in the generation of additional transcription factors.

Question 3

Describe the JAK pathway

Answer 3

An extra celular ligand binds to the JAK protein to activate the pathway. JAK phosphoralates STAT. Phosphoralated STAT dimerizes and crosses in the the nucleus where it activates or inhibits transcription for different genes.

Question 4

Define type 1 interferons (IFN alpha and beta) and explain the three things they do

Answer 4

A sub class of interferon. It has the following three functions1) Act as a paracrine to activate antiviral mechanisium in near by cells stimulating them to make RNAse (possobly through the JAK pathway)2) Increase class 1 MHC expression thus recruting CD8 t cells3) Stimulate NK cell activity

Question 5

What are the most important inflamation cytokines

Answer 5

IL-1, IL6, and TNF alpha

Question 6

What two cells release IFN gamma and what three results can it have

Answer 6

It is released by T cells and NK cells. It increases the microbicidal activity of macrophages, increases the cytotoxic activity of NK cells and stimulates b cells to produce more anti bodies

Question 7

Which complement proteins form the MAC

Answer 7

C5-C9

Question 8

Which complement proteins promote inflamation

Answer 8

C3a, C4a, and C5a (also know as anaphylatoxins as in anaphylactic shock)

Question 9

What is the purpose of the complement pathway promoting inflamation?

Answer 9

many microbes have ways of evading MAC. by promoting inflamation the complement pathway recruites leukocytes to destroy MAC resistant antigens

Question 10

What complement proteins are opsonins

Answer 10

C3b

Question 11

how does the complement pathway promote antibody production?

Answer 11

C3d is recognized by CR2 receptors on b cells which stimulates the production of antibodies

Question 12

How is the complement pathway regulated and why is regulation important

Answer 12

Plasma and cell membrane proteins can stop the complement pathway at various points. This is imporant so self cells can be protected against auto immunity

Question 13

What are the main inhibitors of the complement pathway

Answer 13

C1 Inh, DAF, CD59

Question 14

What complement pathway deficiency causes hereditary angioedema

Answer 14

a deficiency of C1-Inh

Question 15

What complement pathway deficiency causes Paroxysmal nocturnal hemoglobinuria and how

Answer 15

deficiencies in DAF and CD59 allow complement meadiated lysis of RBCs

Question 16

What do deficencies in C1-C4 cause? Why?

Answer 16

This leads to recurrent bacterial infections. This is because all three of the pathways have trouble starting and the opsonin benifit may be lost

Question 17

What do deficencies in C5-C9 cause? Why?

Answer 17

recurent meningococcal and gonococcal infections. This is primarily due to the loss of the MAC complex