CD4+ T cells

Question 1

What are CD4+ T cells?

Answer 1

Part of the adaptive immune system and key regulators of the immune response

Question 2

What is the role of CD4+ T cells?

Answer 2

To recognize antigens presented by MHC Class II molecules and provide help to other immune cells

Question 3

What is the link between dendritic cells and adaptive immunity?

Answer 3

Dendritic cells capture and process antigens and present them via MHC Class II molecules to CD4+ T cells

Question 4

What changes occur in dendritic cells during activation?

Answer 4

Upregulation of MHC Class II co-stimulatory molecules like B7.1 and B7.2 and chemokine receptor CCR7

Question 5

What is the primary function of cytokines produced by CD4+ T cells?

Answer 5

To organize and orchestrate the correct immune response to specific pathogens

Question 6

What are the five subsets of CD4+ T cells?

Answer 6

Th1 Th2 Th17 Tfh follicular helper T cells and Treg regulatory T cells

Question 7

What determines the differentiation of naive CD4+ T cells?

Answer 7

Cytokines produced by dendritic cells in response to pathogens activate specific transcription factors in T cells

Question 8

What cytokines are produced by Th1 cells?

Answer 8

IFN gamma and TNF alpha to enhance cellular immunity

Question 9

What cytokines are produced by Th2 cells?

Answer 9

IL4 IL5 and IL13 to enhance humoral immunity and antibody production

Question 10

What cytokines are produced by Th17 cells?

Answer 10

IL17 to mediate responses against extracellular bacteria and fungi

Question 11

What cytokines are produced by Treg cells?

Answer 11

IL10 and TGF beta to inhibit activation of other T cells and regulate immune responses

Question 12

What is the function of Tfh cells?

Answer 12

To assist B cells in germinal centers by promoting class switching and high-affinity antibody production

Question 13

How do cytokines regulate the differentiation of CD4+ T cells?

Answer 13

Cytokines activate STAT transcription factors which induce specific differentiation programs

Question 14

What is the role of CD4+ T cells in activating CD8+ T cells?

Answer 14

CD4+ T cells stimulate antigen-presenting cells by upregulating co-stimulatory molecules like CD40 and secreting IL2 to activate CD8+ T cells

Question 15

What is the Th1/Th2 balance?

Answer 15

The immune system’s ability to shift between Th1 responses for intracellular pathogens and Th2 responses for extracellular pathogens

Question 16

What pathogens stimulate Th1 responses?

Answer 16

Viruses and intracellular bacteria stimulate Th1 responses

Question 17

What pathogens stimulate Th2 responses?

Answer 17

Helminths and extracellular parasites stimulate Th2 responses

Question 18

What role do Th17 responses play?

Answer 18

They mediate defense against extracellular bacteria and fungi

Question 19

What are thymus-dependent TD antigens?

Answer 19

Protein antigens that require CD4+ T cell help to generate an antibody response

Question 20

What are thymus-independent TI antigens?

Answer 20

Highly repetitive antigens like polysaccharides that can induce antibodies without CD4+ T cell help

Question 21

How can CD4+ T cells contribute to disease?

Answer 21

Excessive Th1 Th2 or Th17 responses can cause autoimmune diseases while excessive Th2 responses can lead to allergies

Question 22

What is the role of HLA Class II alleles in autoimmune diseases?

Answer 22

Certain HLA Class II alleles are linked to autoimmune diseases due to their involvement in CD4+ T cell activation

Question 23

What is the significance of cytokine production by CD4+ T cells?

Answer 23

It drives the differentiation of other immune cells and tailors the immune response to specific pathogens

Question 24

What is the importance of the immunological synapse?

Answer 24

It allows for precise interaction between antigen-presenting cells and CD4+ T cells for effective activation

Question 25

What happens when CD4+ T cells are dysregulated?

Answer 25

Imbalances can lead to conditions like autoimmunity allergies or poor immune responses