28.Molecules of cell-mediated immunity.T-cell receptor. The major tissue-compatibility complex. Epitopes recognized by T lymphocytes.

Question 1

Molecules of cell-mediated immunity – T-cells

Answer 1

• cellular immunity is carried out by T-lymphocytes (T-cells)
• are antigen-specific
• response differs from response of B-cell in 2 ways:
  1. T cells are activated by foreign antigens displayed on surface of APC
  2. Effector B cells, by contrast, secrete antibodies that can act far away.

Question 2

T- cell receptors

Answer 2

• not an immunoglobulin
• 2 types: TCR1 (located under mucosa and skin) and TCR2
• membrane protein
• never releases from the cell

Question 3

B cell receptors and T cell receptors

Answer 3

B cell:
- Y shaped molecule
- heavy + light chain
- directly binds to antigen

T cell:
- alpha and beta chain
- A+B chain
- binds to mhc molecule

Question 4

Major histocompatibility complex

Answer 4

• grp of genes that code for proteins found on surfaces of cell
• divided into MHC class 1 and 2
• MHC 1 - all tissues except placental trophoblast and cells with no nucleuses
• MHC 2 - macrophages

Question 5

Epitopes recognized by T lymphocytes

Answer 5

• T cells recognize the antigen only if its shown by APC
• APC is converted to MHC complexes
• antigens serve as epitopes for t cells to recognize

Question 6

Types of T cells

Answer 6

T killer, T helper, T regulator