Innate Immunity Introduction

Innate immune response

it is ==natural== ==inborn barriers== against invasion by any foreign body

<<Physiological barriers:<<

Skin

Conjunctiva

Respiratory tract

Gastrointestinal tract

Genitaourinary tract

<<Characteristics:<<

  • “Feverishly” ==fast==
  • Natural ==inborn== barriers
  • Less efficient
  • ==Non-specific==
  • ==No memory==
  • Does not require previous exposure

<<Mechanism:<<

  • Physiologic
  • Humoral
  • Cellular
  • Inflammatory

<<Physiological<<

%%Skin%%

- Intact

- Epidermis

  • tight junctions

- Dermis:

  • Sebaceous gland (lactic acid, ammonia)
  • sweat gland

%%Conjunctiva%%

- Blinking reflex

- Tears

  • lysozyme

%%Respiratory tract%%

- mucosal epithelia

  • mucous coated microorganism (sticky)

- cilia

- sneezing

- coughing

- ear

%%Gastrointestinal tract%%

- saliva

  • hydrolytic enzymes

- thick stratified epithelium of adult vagina

- low pH of the stomach

- digestive enzyme

- peristalsis

  • prevent overgrowth of pathogenic bacteria within the lumen of the gut

- normal flora

  • competition
  • bacteriocin
  • antibiotics

- diarrhea

- vomiting

%%Genitaourinary tract%%

- normal flora

  • lactobacilli

- flushing of urine

<<Humoral<<

- %%Lysozyme%%

  • destruction of bacterial cell wall

- %%Lactoferrin, transferrin and ferritin%% (iron binding protein)

- %%Interferons (INFs)%%

  • type I:

• INF α: mononuclear, phagocytes

• INF β: fibroblast

  • type II:

• INF γ: mainly by T cells

  • degradation of viral mRNA
  • prevent viral replication

- %%Complement%%

- %%Acute phase proteins%%

<<Inflammatory<<

(to localize infection)

tissue injury = mast cell degranulation

  • heat
  • pain
  • swelling
  • redness

<<Cellular defense<<

]]A. Phagocytic cells]]

= phagocytosis at the site of Ag invasion

phagocytosis: the process of destroying a particle by cells (==cell eating==)

]]Steps of phagocytosis:]]

  1. Chemotaxis
  2. Migrations
  3. Attachment
  4. Ingestion
  5. Killing (digestion)

]]B. NK cells (cytotoxic)]]

  • large granular lymphocytes
  • CD16 & CD56
  • killing ==virus infected cells (tumor cells)==
  • (ADCC: Antibody Dependent Cellular Cytotoxicity)

}}NK cell killer function}}

  • ==apoptosis== induction in infected and tumor cells
  • killing mechanisms ==same as in cytotoxic T-cells==
  • perforin and granzymes
  • FasL and Fas