for 7 retake

 Great! Here are full sentence answers based on your lecture materials:

Part 1: An accident at the river

1) Two examples of innate and adaptive immune system cooperation:

    •    Example 1: Neutrophils initiating inflammation

The innate immune system responds first by recruiting neutrophils to the wound site. Neutrophils recognize bacterial PAMPs through pattern recognition receptors (PRRs), phagocytose the bacteria, and release cytokines that cause inflammation, which helps recruit more immune cells.

    •    Example 2: B cells producing antibodies

The adaptive immune system becomes involved when B cells are activated by helper T cells. The B cells produce antibodies that are specific to the bacterial antigen, tagging the bacteria for destruction and preventing further spread.

2) What an immune army should “know” or be able to do (SELECT ALL):

✔ A. Be turned on/off (inducible)

✔ B. Remember the enemy (memory)

✔ C. Be trainable (improve over time)

✔ D. Know the difference between self and non-self

All are correct, as the immune system is inducible, specific, has memory, improves with repeated exposure, and must be self-tolerant.

3) Which is true about T and B cell training:

✅ A. T cells need to be able to recognize MHCs as a part of their training.

Explanation: T cells are trained in the thymus to recognize self MHC but not bind too tightly. B cells are trained in the bone marrow. They do not express T cell receptors.

4) Fill in the blank:

Extracellular bacteria would be ingested via phagocytosis by a(n):

✅ A. Antigen-presenting cell

Explanation: Antigen-presenting cells (such as macrophages and dendritic cells) perform phagocytosis on extracellular bacteria to begin the adaptive immune response.

5) Fill in the blank:

Bacterial antigens are processed in phagolysosomes and antigens are presented by:

✅ B. MHC II

Explanation: MHC class II presents extracellular bacterial antigens that have been processed inside phagolysosomes.

6) Fill in the blank:

Antigen presentation to cytotoxic T cells involves:

✅ B. MHC I

Explanation: MHC class I presents endogenous (intracellular) antigens to cytotoxic T cells (CD8+).

Part 2: Giardia infection and vaccine design

Q1) Which finding indicates helminth or protist infection?

✅ A. Eosinophil counts are higher than normal

Explanation: Elevated eosinophils are a hallmark of parasitic infections, especially helminths and some protists.

Q2) Match vaccine types to examples:

    •    Inactivated whole pathogen vaccine → ✅ A

    •    Subunit protein vaccine → ✅ B

    •    Live attenuated whole pathogen vaccine → ✅ C

    •    Subunit RNA vaccine → ✅ D

These correspond to the types: killed pathogen (A), purified protein (B), weakened but live microbe (C), and genetic vaccine using mRNA (D).

Part 3: SARS-CoV-2 and Viral Infections

Q1) Vaccination targets which immune system arm?

✅ Adaptive

Explanation: Vaccines train the adaptive immune system, especially B and T cells, to recognize and remember viral antigens like those from SARS-CoV-2.

Q2) B cell antigen recognition and presentation:

Free-floating virus antigens are presented via:

✅ A. MHC II

Explanation: B cells internalize antigens recognized by their B cell receptor (BCR) and present them via MHC II to helper T cells.

Q3) What helps fully activate B cells? (SELECT ALL):

✅ B. B cells interact with Th2 cells

✅ D. MHC II and TCRs must match (bind)

Explanation: B cells require help from Th2 cells, and successful binding between B cell MHC II and the T cell receptor (TCR) is required.

Q4) ADCC definition:

✅ A. ADCC

Explanation: Antibody-dependent cellular cytotoxicity (ADCC) involves antibodies coating a virus and recruiting macrophages or NK cells to destroy it.

Q5) High-risk COVID-19 patient receiving injected antibodies =

✅ C. Artificial passive immunity

Explanation: Injected antibodies are a form of passive immunity, and since they're made outside the body, it is artificial.

Q6) Correct description of B cell process:

✅ C. Affinity maturation happens when the Fab region gets better at binding antigen

Explanation: Affinity maturation improves the antigen-binding Fab region of the antibody through somatic hypermutation.

Part 4: HIV, Cancer, and More

Q1) What happens in HIV patients with low CD4 counts?

✅ B. Helper T cells are targeted and destroyed by HIV

Explanation: HIV specifically infects CD4+ helper T cells, impairing the ability of the immune system to coordinate a response.

Q2) Two maternal protections for infant:

    •    Breastfeeding (IgA antibodies)

    •    Placental transfer of IgG antibodies

Explanation: Infants get passive immunity through maternal antibodies passed via the placenta (IgG) and breast milk(IgA).

Q3) Suspected immune-related cancer – blood test findings:

    •    a. WBC #1 type: Helper T cell (CD4+)

Explanation: Helper T cells are essential for coordinating immune responses. If CD4+ cells are deficient, it could indicate a problem like HIV or T-cell lymphoma.

    •    b. WBC #2 type: B cell or plasma cell

Explanation: Abnormal numbers of plasma cells (antibody-producing B cells) might indicate multiple myeloma or lymphoma, which are immune-related cancers.