Antigen Processing and Presentation

Question 1

What part of the antigen T cells recognize

Answer 1

Peptides/ amino acid sequence (not whole antigen)

Question 2

3 types of professional antigen presenting cells

Answer 2

Macrophages
Dendritic cells
B cells

Question 3

Steps of exogenous pathway

Answer 3

1. Endocytosis of protein antigens by antigen presenting cells
2. Antigen is processed into peptides by endsomes or lysosomes
3. MHC class II molecule binds peptide within endocytic vesicle
4. MHC class II molecule is expressed on surface of antigen presenting cell

Question 4

Steps of endogenous pathway

Answer 4

1. Intracellular protein is degraded into peptides by proteasome
2. Transporter associated with antigen processing (TAP) transports peptide to rough endoplasmic reticulum
3. MHC class I binds peptide
4. MHC class I molecule is expressed on surface of cell

Question 5

Role of invariant chain in exogenous pathway

Answer 5

Invariant chain blocks MHC class II binding of endogenous antigen and is degraded prior to peptide binding

Question 6

Cross presentation

Answer 6

Diverting engulfed antigen from virus-infected cell or tumor cell to endogenous pathway, enabling presentation by MHC class I

Question 7

Cell that can cross present

Answer 7

Dendritic cell

Question 8

Are professional antigen presenting cells necessary for MHC class I presentation to T cytotoxic cells?

Answer 8

No- other MHC class I containing cells can present antigen to T cytotoxic cells