Exam 3 - Chapter 28

Type I Hypersensitivity

Immediate

Type I Hypersensitivity Immune Mechanism

IgE sensitization of mast cells

Type I Hypersensitivity Time of Latency

Minutes

Type I Hypersensitivity Examples

• Reaction to bee venom (sting)

• Hay fever

Type II Hypersensitivity

Cytotoxic

Type II Hypersensitivity Immune Mechanism

IgG interaction with cell surface antigen

Type II Hypersensitivity Time of Latency

Hours

Type II Hypersensitivity Example

Drug reactions (penicillin)

Type III Hypersensitivity

Immune complex

Type III Hypersensitivity Immune Mechanism

IgG interaction with soluble or circulating antigen

Type III Hypersensitivity Time of Latency

Hours

Type III Hypersensitivity Example

Systemic lupus erythematosus (SLE)

Type IV Hypersensitivity

Delayed type

Type IV Hypersensitivity Immune Mechanism

Th1 inflammatory cell activation of macrophages

Type IV Hypersensitivity Time of Latency

Days (24-48 hours)

Type IV Hypersensitivity Examples

• Poison Ivy

• Tuberculin test

• Contact dermatitis

Type I Hypersensitivity Process

1. Allergen bound by B cell

2. Allergen processed and presented to Th2 cell

3. Th2 cell provides B cell help

4. B cell forms plasma cells

5. Plasma cell produces IgE

6. IgE sensitizes tissue mast cells by binding to surface IgE receptors

7. Subsequent exposure to antigen

8. Antigen cross-links 2 antibody molecules

9. Release of allergic mediators

Type I/Immediate Hypersensitivity encompasses…

Allergies from mild to life threatening

Type IV Hypersensitivity Method

Cell-mediated hypersensitivity characterized by tissue damage (hives, blisters) due to inflammatory responses produced by Th1 inflammatory cells

Superantigens

Proteins capable of eliciting a strong response by interacting with T cell receptors (TCRs)

Superantigen activated T cells may produce…

systemic diseases characterized by systemic inflammatory reactions

Autoimmune diseases occur when…

T and B cells are activated to produce immune reactions against self proteins

Autoimmune diseases result in…

host tissue damage

Autoantibodies

Antibodies that interact with self antigens

Some autoimmune diseases are caused by…

autoantibodies

Examples of diseases caused by autoantibodies

• Systemic lupus erythematosus (SLE)

• Type 1 diabetes mellitus

• Rheumatoid arthritis

Severe combined immune deficiency syndrome (SCID)

Serious, congenital deficiency of both B & T cells

What impact does SCID have on infected human lifes?

Patients live a restricted life, limiting their exposure to pathogens

Acquired immunodeficiency syndrome (AIDS)

Caused by HIV infection that progresses and kills CD4+ T cells

What impact does AIDS have on infected human lifes?

Patients are prone to opportunistic infections and cancer, since they are deficient in T cell help

Bacterial immunization recommendations for infants and children in the US

• Haemophilus influenzae type B (Hib)

• Meningococcal (Neisseria meningitidis)

• Pneumococcal (Streptococcus pneumoniae)

• Tetanus, diphtheria, pertussis (DTaP, Tdap)

Viral immunization recommendations for infants and children in the US

• Hepatitis A virus

• Hepatitis B virus

• Human papillomavirus (HPV)

• Influenza virus

• Inactivated poliovirus (IPV)

• Measles, mumps, rubella (MMR)

• Rotavirus

• Varicella virus (chicken pox)

Immunotherapy

Harness cells and other components of the immune system to fight or prevent diseases

Example of immunotherapy

Anticancer vaccines

Mechanisms of action of major antibacterial agents

• Cell wall synthesis

• Cytoplasmic membrane structure and function

• Folic acid metabolism

• DNA gyrase

• DNA-directed RNA polymerase

• RNA elongation

• Protein synthesis

  • 50S inhibitors

  • 30S inhibitors

  • tRNA

• Lipid biosynthesis

Antibiotics that target cell wall synthesis

• Cycloserine

• Vancomycin

• Bacitracin

• Penicillins

• Cephalosporins

• Monobactams

• Carbapenems

• Teixobactin

Antibiotics that target cytoplasmic membrane structure and function

• Polymyxins

• Daptomycin

Antibiotics that target folic acid metabolism

• Trimethoprim

• Sulfonamides

Antibiotics that target DNA gyrase

• Quinones

  • Nalidixic acid

  • Ciprofloxacin

• Novobiocin

Antibiotics that target DNA directed RNA polymerase

• Rifampin

• Streptovaricins

Antibiotics that target RNA elongation

Actinomycin

Antibiotics that target protein synthesis 50S inhibitor

• Erythromycin

• Chloramphenicol

• Clindamycin

• Lincomycin

Antibiotics that target protein synthesis 30S inhibitors

• Tetracyclines

• Spectinomycin

• Streptomycin

• Gentamicin

• Kanamycin

• Amikacin

• Nitrofurans

Antibiotics that target protein synthesis tRNA

• Mupirocin

• Puromycin

Antibiotics that target lipid biosynthesis

Platensimycin

Consideration for what antibiotic to use/antibiotics differ in

• Efficacy

• Toxicity

• Spectrum

• Cost effectiveness

• Route of administration

Antimicrobial drugs that target nonbacterial pathogens

• Antiviral drugs

  • Host or viral targets

  • Interferons

• Drugs that target eukaryotic pathogens

Antimicrobial drug resistance

Acquired ability of a microorganism to resist the effects of an antimicrobial agent to which it was formerly susceptible

How can antimicrobial drug resistance happen?

• Genetically encoded on bacterial chromosome

• Contain drug resistance genes on horizontally transmitted R plasmids (horizontal gene transfer)

• Overuse of antibiotics

• Consumption of meat products where antibiotics were used as a feed additive

Potential strategies for minimizing or combatting antimicrobial drug resistance

• Change drug formula when widespread resistance develops

• Reducing antibiotics provided as feed additives in livestock & poultry

• Only use drugs for treatment of susceptible pathogens

• Use drugs in high enough concentrations and sufficient lengths of time to eradicate pathogen before mutants can form

• Select for antibiotics that interact with unexploited targets

• Develop antibiotics that thwart antibiotic resistance mechanisms

• Drug combination therapy