Immunity obtained and type of immune response

• Innate immunity（Non-specific, natural）

  Nonspecific ability to defense against pathogen infection.

• Adaptive immunity（Specific, acquired）

  Specific ability acquired following exposure to the microorganism etc．

Anatomic 解剖的 barriers

• External/First line of defenses

• Epithelial 上皮的 Barrier： Skin， Mucous membranes 黏膜

  ※ Conjunctivae 结膜, gastrointestinal 胃肠, respiratory, urogenital 泌尿生殖的 tracts ※ Secretions (saliva, tears, urine) --wash/trap/inhibit growth ※ Cili 纤毛

  • 结构

Physiologic barriers

• Temperature---Fever

• pH--Stomach, vagina阴道

• microflora 显微植物群 of GI tract, skin

• Chemical Mediators

  Defensins防御素-Secreted by Epithelia 上皮 Hydrolytic enzymes of Saliva 唾液水解酶 Lysozyme溶菌酶 in tears Interferons干扰-viral infection

peptide antibiotics 肽类抗生素；intraepithelial lymphocytes 上皮内淋巴细胞；endothelial 内皮的

Cellular Barriers

Phagocytosis吞噬细胞作用： Cells flowing around the pathogen and engulfing吞没 it , and finally killing it.

Cells: Neutrophils 嗜中性细胞,

Macrophages巨噬细胞, Natural killer cells

• 1. Phagosome 吞噬小体 and lysosome溶酶体
• 2. Mononuclear phageocyte system （MPS) 单核吞噬细胞系
• 3. NK cell
• 4. Pathogen-associated molecular (PAMPs) & Pattern-recognition receptors (PRRs)

Lipopolysaccharides(lps)

• Large molecules found in outer membrane of Gramnegative bacteria
• Comprised of a lipid and saccharide component
• Highly immunogenic
• Recognized by TLR4
• Can cause septic shock and lead to death
• Often referred to as Endotoxin since it is not secreted but is a byproduct of bacterial lysis
• Great variability among different bacterial strains