Immunity Flashcards
What are the two types of immunity?
Non-specific (natural, innate) immunity
- can’t distinguish between pathogens
- causes fever (quick) but no memory
Specific (acquired, adaptive) immunity
- different isn’t pathogen by antigens
- specific response for each pathogen (takes longer)
What are the key features of non-specific immunity?
- Skin: mechanical barrier, acid pH, and temp reg.
- Mucous membrane: cilia, lysosomes, and pH reg
- Iron-binding proteins (transferrin)
- Phagocytosis by WBC and macrophages
What is humoral immunity?
- involves circulating antibodies in body fluids to attack specific pathogens
- antibodies are produced by B-lymphocytes in response to antigens
- Antibody production is regulated by T-helper and T-suppressor cells
What is the role of B-lymphocytes in humoral immunity?
- B-lymphocytes produce antibodies
- they require antigen-presenting cells for activation
- T-helper cells help regulate antibody production
What is an antibody (Ab) and it’s function, what is it produced by and what are the 5 types?
An immunoglobulin produced in response to an antigen
- can distinguish foreign macromolecules from body cells
- Produced by B-cells (plasma cells)
- Includes five types: IgG, IgA, IgM, IgE, IgD
What is an antigen (Ag), what does it stimulate, what can it be made of and what does it have?
A substance recognized as “non-self” by the body
- Stimulates antibody production
- Can be a protein, glycoprotein, lipoprotein, or polysaccharide
- Bacterial cells have antigens like capsules, flagella, and cell walls
What are the properties of IgG?
- main antibody in immune response
- can cross the placenta to protect the newborn
- has 2 combining sites for antigen attachment
- binds phagocytes and macrophages for destruction
What are the properties of IgM?
- Made of five units joined together
- First immune globulin produced in early immune responses
- Does not cross the placenta
What is the primary immune response?
- Occurs when an antigen is introduced for the first time
- Delayed antibody production (5-10 days), peaks at 3 weeks, then drops
- Initial response shows a lag period
What is the secondary immune response?
- Occurs when the antigen is reintroduced
- Faster antibody production (2-3 days) with a longer-lasting peak
- Basis for booster injections and immunization
What is the serological reaction?
- Detects antibodies in a serum sample
- Quantifies antibody levels through titration
- Can identify unknown microorganisms with known antisera
What is cell-mediated immunity (CMI)?
- Involves T-cell subpopulations without antibodies
- Active against intracellular organisms (e.g., viruses, parasites)
- Important in defense against tumor cells and foreign cells (e.g., transplants)
What are Antigen Presenting Cells (APCs)?
- Immune cells that display antigens to trigger immune responses
- Drive humoral or cell-mediated immunity, depending on the antigen type
How does the immune system vary?
- It can be affected by factors such as age, race, stress, and nutritional status
- These factors can influence the strength and effectiveness of the immune response
What happens in allergic and hypersensitivity reaction?
- overreaction to antigens without infection
- can lead to anaphylaxis
What are the four harmful effects of the immune response?
- Allergy and hypersensitivity
- Auto-immune diseases
- Immunodeficiency states
- Graft rejection
What are auto-immune disease?
- the immune system attacks the body’s own tissue
- formation of auto-antibodies that target self-materials
What are immunodeficiency states?
- Lack of ability to produce antibodies or cell-mediated immunity
- Can result from congenital issues, irradiation, or diseases like AIDS
What is graft rejection?
- The immune system recognizes transplanted organs (e.g., kidney, heart) as foreign and rejects them
- Requires immunosuppressive drugs to prevent harm to the patient
What is passive immunization and what are the risks?
- Administration of preformed antibodies (IgG) against a pathogen
- Immediate protection but short-lived (lasts about 10 days for animal-derived IgG)
- Risks: hypersensitivity reactions (serum sickness, anaphylaxis)
What is the difference between human and animal-derived IgG in passive immunization?
- Animal-derived IgG: foreign to the immune system, carries risk of hypersensitivity
- Human-derived IgG: shorter-lasting, but no risk of hypersensitivity
What is active immunization?
- Stimulating the body’s immune system by administering a vaccine (antigen or immunogen)
- Longer-lasting protection compared to passive immunization
- produces memory cell
Active immunization - What are live attenuated vaccines?
- Modified viruses that cause mild illness to stimulate immunity
- Provide both local (IgA) and humoral (IgG) immunity
- Can cause serious disease in immunocompromised individuals
Active immunization - What are killed vaccines, subunit vaccines, and toxoids?
- Non-infective vaccines requiring multiple injections for effective immunity
- Toxoids (e.g., tetanus) are administered with adjuvants to enhance immunity
Active immunization - What are recombinant vaccines and give an example?
- Produced by DNA technology, avoiding live virus risks
- Example: Hepatitis B vaccine
Active immunization - What are adsorbed vaccines and give an example?
- Mixed with inorganic salts (e.g., alum) to ensure prolonged immunity
- Example: Tetanus and diphtheria toxoids
Active immunization - What are conjugate vaccines and give an example?
- Polysaccharide capsules linked to a protein to make them immunogenic
- Example: Haemophilus influenzae type b vaccine
Active immunization - What are combined vaccines?
- Vaccines containing multiple components (e.g., multiple live or killed vaccines)
- Facilitate administration by combining different vaccines
What is combined active-passive immunization and give examples?
- Provides both immediate protection through passive immunization and long-term immunity via active immunization
- Example: Tetanus, hepatitis B, and rabies exposure
What is the history and significance of antibiotic resistance?
- Antibiotics were groundbreaking in the 1940s and 1950s but have become less effective over time
- Resistance leads to higher morbidity, mortality, and healthcare costs
What is intrinsic resistance?
A predictable resistance based on the antibiotic’s mechanism of action and microbial characteristics
What is the production of inactivating enzymes of antibiotics?
bacteria produces enzymes to inactivate the bacteria
What are the main reasons for antibiotic resistance?
- Overuse in agriculture and aquaculture
- Misuse in human medicine (especially in developing countries)
- Immunocompromised patients harboring resistant bacteria
What is acquired resistance?
- When a previously susceptible organism becomes resistant to an antibiotic
What are the key mechanisms of acquired antibiotic resistance?
- Alteration in drug target
- Production of inactivating enzymes
- Decreased antibiotic uptake
What are the main types of antibiotic resistance mechanisms?
- Altered Target
- Inactivating Enzymes
- Decreased Uptake
- Efflux
What is transformation in antibiotic resistance?
Uptake of free DNA from the environment and incorporation into the bacterial genome
What is the resistance mechanism for decreased uptake of antibiotics?
- Altered outer-membrane proteins that stops antibiotic from entering
How can antibiotic resistance genes be transmitted?
Through the bacterial chromosome or extrachromosomal entities like plasmids
What is the resistance mechanism for efflux?
- New membrane transport system
- Affects Erythromycin, fluoroquinolones, tetracycline
What is conjugation in antibiotic resistance?
- Exchange of DNA via direct cell-to-cell contact using conjugative pili
- Involves plasmids that replicate independently in bacteria
What is transduction in antibiotic resistance?
Transfer of genetic material via bacteriophages (viruses) that accidentally carry bacterial DNA
What is the chromosomal alteration mechanism for antibiotic resistance?
Mutation of chromosomal genes that encode the antibiotic target site or control pathways like efflux, permeability, and uptake
What is the Mar phenotype in antibiotic resistance?
- A multiple antibiotic resistance phenotype linked to the mar locus on bacterial chromosomes
- Activated by mutations, resulting in resistance to multiple drugs
What is transposition in antibiotic resistance?
- Movement of antibiotic resistance genes between DNA molecules (chromosomes to plasmids)
- Conjugative transposons and integrons play key roles in this process
