Bridging Innate and Adaptive Immune

Question 1

Cytokines

Effects

Answer 1

Regulation of growth
Differentiation
Gene expression of different cell types

Question 2

Phagocytosis: Basics

What it does and process

Answer 2

• Phagocyte engulfs particle
• Helped by opsonins which label the target to engulf
• Cytoplasm flows around particle, fuses with it = pseudopodia
• Pseudopodia increase in oxygen, oxidative burst
• Phagosome moves to center of cell

Question 3

Phagocytosis: Fusion and Digestion

Process

Answer 3

• Cytoplasmic granules fuse with phagosome = turn into phagolysosome
  Degradation
• Granule proteolytic enzymes: oxygen independent
• Toxic peroxidase: oxygen dependent

Question 4

Antigen Presenting Cell (APC)

What are they? Who are they?

Answer 4

Cell that can take up, break down, display parts of pathogen to other cells

Macrophages, dendritic cells, B cells
Present antigens to T cells

Question 5

Antigen Definition

Answer 5

Substance that can be specifically bound by an antibody or T cell receptor

Question 6

Peptide Definition

Answer 6

Antigen that is bound by a T cell receptor

Question 7

Antigen Bound by Antibody, Immunoglobin, or B cell Receptor

Answer 7

Sugars, phospholipids, nucleic acids, proteins

Question 8

Immunogen Definition

Answer 8

Molecules that stimulate immune response, important for deciding what antigen we pick for a vaccine

Question 9

Epitopes

What are they and different recognition by cells

Answer 9

Specific determinant on the antigen that can be recognized by the immune system

• Immunogens can have mulitple epitopes
  B cell: recognizes both linear and discontinuous/conformational epitopes
  T cell: recognizes linear epitopes as part of MHC proteins, immunogen must be degraded

Question 10

Major Histocompatibility Complex Basics

Answer 10

Genetic region in living things responsible for presenting antigen lymphocytes
- Expressed in antigen presenting cells or all nucleated cells

“Human leukocyte antigen (HLA)” molecules present both self and foreign antigens

Question 11

MHC Gene Categories

Three classes

Answer 11

MHC Class I: antigen recognition; HLA-A, B, C of chromosome

MHC Class II: antigen recognition; HLA-D of chromosome DP, DQ, DR

MHC Class III: secreted proteins in area between class I and II genes

Question 12

MHC Genes

Answer 12

Codominantly expressed
Travel together during inheritance - haplotype (genes for A, B, C, DR, DP, and DQ) from each parent

Question 13

MHC Class I

Answer 13

Binds peptides within cells
- of internal origin (virus/tumor)
- Transport/present to plasma membrane for CD8 T/cytotoxic T cells
- Found on all nucleated cells

Question 14

MHC Class II

Answer 14

Bind peptides within cells
- external origin (bacteria)
- transport and present to plasma membrane for CD4 T cells/helper T cells
- Only found on antigen presenting cells

Question 15

What Causes Increase in MHC Expression?

Answer 15

Inflammation and adaptive responses

Question 16

MHC Structure

4 main things

Answer 16

• Extracellular binding groove, immunoglobin domains, transmembrane segments
• Polymorphic sites mostly in or near binding cleft
• Non-polymorphic sites in Ig domains bind CD4 and CD8 on T cells, docking mech.
• Filled with “self” peptides when no infection, marks that cells are healthy and normal

Question 17

Role of MHC

Answer 17

Main: antigen presenting
- pick up degraded peptides in cells, transport to plasma membrane and present to T cells that recognize it

Differences: related to mechanism of how antigen is transported to surface

Question 18

Class I MHC-Peptide Interaction

Answer 18

Synthesized in endoplasmic reticulum
Endogenous pathway: antigens synthesized in same cell as Class I molecules
- self antigens, intracellular peptides
- peptides that bind to Class I molecules 8-11 amino acids, from partial digestion of proteins

CD8 T cells always check cell surface for non-self antigens, produces cytokines if they are present

Question 19

Class II MHC-Peptide Interaction

Answer 19

Synthesized in endoplasmic reticulum
Exogenous pathway: antigen taken into the cell from outside by phagocytosis or endocytosis
- Invariant chain: prevent binding of endogenous peptides within endoplasmic reticulum
- Must be transported from ER to endosomal compartment to bind with peptide

Question 20

Significance of MHC

Answer 20

• Determinant of transplant compatibility
• Certtain alleles protective for infectious diseases
• Certain HLA antigens increase autoimmune disease risk
• Role in cancer prevention or development