Cytokines & Stuff

IL-18/IL-12

T_H1 Cells → release cytokines that stimulate cell mediated response

IL-10/IL-4

T_H2 Cells → release cytokines that stimulate humoral response

Humoral Immune Response

Antibody Mediated

• Extracellular bacteria infection are more likely to illicit this.

• T_H2

Cell-Mediated Immune Response

Cytotoxic T-Cells

• Viral infections will cause stronger cell mediated response

• T_H1

IL-2

T_H1 Cell - Cell mediated

Proliferation of antigen-activated CD8⁺ T cells into T_c cells → Killing of infected target cells

TNF-a

T_H1 Cell - Cell mediated

Increased phagocytosis by macrophages and neutrophils → Killing of ingested pathogen

IFN - ɣ

T_H1 Cell - Cell mediated

Increased Intracellular killing by macrophages and neutrophils → Killing of ingested pathogen

Can suppress T_H2 cytokines

IL-10, IL-13

Suppress T_H1 cytokines

IL- 4

T_H2 - Humoral Response

Proliferation of antigen-activated B cells

IL-6

T_H2 - Humoral Response

Differentiation of B cells into plasma cells and secretion of antibody

Killing action of IL-4, IL-6 in T_H2 - Humoral Response

Secreted antibody binds to extracellular target antigen → opsonization, phagocytosis, and killing of ingested pathogen

Complement activation by classical Pathway → C3b → opsonization, phagocytosis, and killing of ingested pathogen or MAC formation and microbial lysis

C3b

Opsonization (enhancing phagocytosis)

opsonization, phagocytosis, and killing of ingested pathogen

MAC formation and microbial lysis

TNF-a/IFN - ɣ

Pro-Inflammatory cytokine; Stimulates macrophages

IFN- ⍺/β - Viral defense

Promotes antiviral activities in neighboring cells

Promotes proliferation of NK Cells

Inhibits Ribosome binding → Prevents host cell protein production → Apoptosis of infected cell → Prevents viral replication

Degrades RNA → Prevents protein production → Prevents viral replication

Changes in membrane components → Blocks viral attachment and entry → Prevents viral replication

IL- 2 *

Induces clonal expansion & differentiation of T-cells*

IL-4, IL-5, IL-13

Induces clonal expansion & differentiation of B-cells

Live-attenuated

Has the virus but it’s been deactivated in a way that doesn’t cause diseases. illicits good immunity and can sometimes revert back to WT & Cause diseases

e.g. MMR, chickenpox, Sabin polio

Inactivated whole virus/cells

Can’t cause infection & really effective

e.g. Salk polio, rabies

Subunit vaccines

Contains antigen(s) but not whole cells. The problem is generating a long immune response

e.gHepatitis B, meningitis, among others

Toxoid

Vaccines against toxins

e.g. DTaP against diptheria, tetanus and pertussis toxins

mRNA

Giving copy of mRNA’s & person receiving vaccine is making the protein. Easier to change nucleotide sequence if there’s change in virus.

Pfizer, Moderna vaccines

Examples of Auto-Immune diseases

Type I diabetes mellitus

Rheumatoid arthritis

Multiple sclerosis