2.8 Roles of the innate and adaptive immune system

Innate vs Adaptive immune system response

Innate : Immediate general response to pathogens

Adaptive: a learned, highly specific defense that develops over a period of time and forms a long lasting immune memory

Innate immunity

Innate (non-specific) immunity:

first line of defence

• mucosa and secretions, skin

• Immune cells (phagocytes and NK cells)

• cytokines and chemokines

Responds same way to all threats

Acts rapidly (seconds to hours)

Never changes over lifetime

relies on conserved (general) features of pathogens

Adaptive immunity

Adaptive (specific) immunity

The body’s last line of defence

• lymphocytes (T- and B-cells)

• antibodies

responds specifically to each pathogen

acts slowly (days-weeks)

Constantly updating, forms lasting memory

Relies on variable (specific) features of pathogen for recognition

Steps of Innate mechanisms

1. Pathogens or dead/damaged somatic cells are detected by somatic cells

2. Immune cells trigger cytokines including chemokines

3. Leukocytes destroy pathogen or dead/damaged somatic cells (NK cells murder cells, phagocytes engulf/digest cells)

What are cytokines and chemokines

Cytokines and chemokines are both immune cells

cytokines trigger:

• inflammation

• somatic cell growth/repair

• fever

Chemokines trigger:

• recruitment and guide phagocytes, NK cells and Lymphocytes

Leukocytes - Phagocytes and NK cells (what are they)

NK cells (natural killer cells) :

• contact foreign/problematic cells

• chemically induce apoptosis or cellular lysis (tells cell to end itself)

Phagocytes:

• flexible movement allows to patrol blood

• approach problematic cells and engulf via phagocytosis

• digest with lysosomal enzymes

• may present remains (antigens) to adaptive immune cells

Both release additional cytokines and chemokines which amplifies response