Question

. Explain the difference between innate and adaptive immunity.
2. What is an antigen and how does it relate to antibodies?
3. Why is inflammation important in fighting infections?
4. How do vaccines help the immune system?
5. Give one example of an autoimmune disease and describe what happens in the body

Answer 1

1) Innate vs adaptive immunity
- Innate immunity: immediate, nonspecific defense present from birth. Includes physical barriers (skin, mucous), phagocytes (macrophages, neutrophils), natural killer cells, complement, and inflammatory responses. It reacts quickly but does not form long-term memory.
- Adaptive immunity: slower to develop on first exposure, highly specific to particular antigens, mediated by B and T lymphocytes. B cells make antibodies (humoral immunity); T cells kill infected cells or help other immune cells (cell-mediated immunity). Adaptive responses create memory cells that give faster, stronger responses on re‑exposure.

2) What is an antigen and how it relates to antibodies
- An antigen is any molecule (often a protein or polysaccharide) that the immune system recognizes as foreign or unusual. Antigens contain specific regions called epitopes.
- Antibodies are proteins produced by B cells that bind specifically to epitopes on antigens. Binding can neutralize pathogens, mark them for phagocytosis (opsonization), or activate complement, helping eliminate the antigen-bearing organism.

3) Why inflammation is important in fighting infections
- Inflammation is a coordinated local response that increases blood flow and vascular permeability to bring immune cells, antimicrobial proteins, and nutrients to the site of infection. It helps isolate the invader, promote phagocytosis and killing of microbes, and initiates tissue repair. (Note: if inflammation is excessive or chronic it can cause tissue damage.)

4) How vaccines help the immune system
- Vaccines present a safe form of an antigen (killed/attenuated pathogen, protein subunit, viral vector, mRNA, etc.) so the adaptive immune system mounts a response and forms memory B and T cells without causing the disease. On future exposure to the real pathogen, the immune system responds faster and more effectively, preventing illness or reducing severity. Vaccination also contributes to population-level protection (herd immunity).

5) Example autoimmune disease — Type 1 diabetes
- What happens: the immune system (especially autoreactive T cells) mistakenly attacks and destroys insulin-producing beta cells in the pancreatic islets. Loss of beta cells causes deficient insulin production, leading to high blood glucose (hyperglycemia).
- Consequences: symptoms like increased thirst and urination, weight loss, and risk of acute (ketoacidosis) and long-term complications (cardiovascular disease, neuropathy, kidney damage). Treatment focuses on replacing insulin and managing blood glucose; underlying autoimmunity currently cannot be fully cured.