NBME Final Exam

Question 1

Characteristics of the innate immune response

Answer 1

1. Pattern Recognition
2. Limited repertoire
3. No memory
4. Starts in hours
5. Stimulates adaptive immune response

Question 2

Characteristics of adaptive immune response

Answer 2

1. Antigen specificity
2. Wide diversity
3. Memory B cells
4. Starts after days
5. Down regulates inflammation

Question 3

Primary effectors cells of the adaptive immune system

Answer 3

Lymphocytes (B cells, Natural Killer cells and T cells)

Question 4

T cells

Answer 4

Can be TH1, TH2, Treg, Tctl

Are identified by T cell receptor and CD3

CD8+ or CD4+

Question 5

T cell production and maturation

Answer 5

T cells are produced in the bone marrow and migrate to the thymus to undergo maturation through positive selection and negative selection processes

Question 6

Describe the T-cell receptor complex

Answer 6

TCR is composed of alpha chain (like light chain) and beta chain (like heavy chain)

TCR recognizes short peptide antigens presented by class 1 MHC. The antigen it responds to is determined by three hypervariable regions

TCR is associated with either CD8 or CD4 and is complexed with CD3 which functions in signal transduction for the receptor (receptor cannot signal)

Additionally zeta chains help signal too

Question 7

Varieties of T lymphocytes

Answer 7

• CD8+ interact with MHC class 1 and kill infected cells and tumor cells
• CD4+ interact with MHC class 2 and are TH cells (TH1, TH2, or TH17)
• CD25+ are Treg which regulate Tctl and Th, they are a subset of CD4+ cells