Innate Immunity

Lines of Defense• First - non-specific (NS)

barriers, normal flora• Second – Non-Specific

immune cells, proteins, processes

• Third - specific immune cells and antibodies

Nonspecific First Lines of Defense

Outer Skin and Flora• Outer skin is a thick, salty,

and dead barrier• Intact skin• Sloughing off dead skin• Microbial anatagonism

Chemical

• pH = 5.0 due to fatty acids in secretions from oil glands (sebum)

• Lysozyme (nasal, saliva, tears and sweat) favors

• Salt: draws out water• Lactoferrin: binds iron• Antimicrobial polypeptides: chains of 40

amino acids, dermicidins• Staphylococcus favored

Mucous Membranes: Respiratory

• Thin epithelium• Goblet cells: secrete

mucous• Ciliated columnar

cells

Digestive Tract• Protective features – digestive

enzymes, • Strong acid: HCl• Peristalsis• Bile: detergent• Stomach selects acidophilic

Streptococcus• Neutral intestines, colon host

over 400 species:• Gram Positive Anaerobes - e.g.

Clostridium• Gram Negative Enterics - e.g.

Escherichia

Urinary Tract/ Vaginal TractKidney to bladder sterileUrethra/opening - skin and intestinal bacteriaAcidic urine and flushing reduces pathogens

Menstrual – acid-producing LactobacillusHormones makes more susceptible to STDs, increase pH of vaginaAntibiotics make more susceptible to yeast

Normal - Indigenous - FloraInfect newborns within a year Flora keep immune system alertOut-compete or kill pathogensWrong place - some opportunistic

Antibiotics DO NOT distinguish between “good” and “bad”

Second Lines of Defense

• Blood complex liquid tissue• Cells found in blood• Plasma has chemical components

Non-Specific Immune Cells -Phagocytes

• Basophils: release chemicals• Eosinophils: parasitic worms

and allergic reactions• Neutrophils – most

abundant, circulating• Macrophage – tissue,

inflammation• Microglia – specialized brain

phagocytes• Kupffer: Liver• Alveolar• Dendritic : found in skin and

mucous

Diapedsis

• NK lymphocytes• Viral infected cells• tumors

Phagocytosis

Surround agent with pseudopods - engulf

Digest using lysozymeand hydrogen peroxide

Phagocytosis

Second Lines of Defense:Non-Specific Blood Proteins

• Transferrin - store iron, • Lactoferrin-hide from pathogens• Interleukins - induce fever to inhibit

pathogens, raise temperature, stimulate white blood cells, slow rate of growth of bacteria.

Complement – series of proteins to lyse bacteria

Interferons – small antiviral proteins, inhibits spread of

infection

Non-Specific Inflammation Process

Tissue is breached -injured

Vasodilation - delivers blood, immune cells

Permeability - delivers blood proteins

Chemotaxis - phagocytes attracted to injury

Phagocytosis -consumption of pathogens

Vasodilation

• Histamines• Prostaglandins• Leukotrienes

Edema and pain: aspirin act as anti prostaglandins

Interleukins

• - induce fever to inhibit pathogens, raise temperature, stimulate white blood cells, slow rate of growth of bacteria.