Advanced Molecular Cell Biology - Immunology I

Comprehensive flashcards covering the basics of innate and adaptive immunity, first lines of defense, cellular components of blood, and the mechanisms of immune tolerance.

How is immunity defined in the context of this lecture?

Immunity is the state of being insusceptible or resistant to a noxious agent or process, especially a pathogen or infectious disease.

What are some of the diverse categories of pathogens listed in the notes?

Bacteria, fungi, parasites, 'foreign bodies', 'foreign' tissues, and 'unwanted' cells such as those undergoing necrosis, apoptosis, or cancer.

Which enzyme found in tears and saliva is responsible for digesting bacterial cell walls?

$$\text{Lysozyme}$$

What are defensins?

Small anti-microbial peptides found in secretions that attack the cell walls of bacteria.

How does stomach acid act as a first line of defence?

$\text{HCl}$ (hydrochloric acid) secreted by parietal cells lowers the pH, which activates proteases such as $\text{pepsin}$ to kill pathogens.

What is the biological role of cilia in the windpipe?

Cilia are very fine hairs that move mucus and trapped particles (like bacteria, dust, or smoke) away from the lungs.

Which condition is characterized by a mutation in a chloride ion channel that results in thickened mucus, leading to lung infections?

Cystic fibrosis

What are PAMPs and DAMPs?

PAMPs are Pathogen-Associated Molecular Patterns used to identify foreign pathogens. DAMPs are Damage-Associated Molecular Patterns used to identify damaged 'self' cells.

Give two examples of molecular patterns used by the innate immune system to recognize bacteria.

1. Lipopolysaccharides (LPS) found in Gram-negative bacterial cell walls. 2. Peptides containing formylated-methionine, an amino acid used only by bacteria.

What is the largest family of receptors used to detect PAMPs in humans?

Toll-like Receptors (TLRs), of which there are 10 types in humans.

Which downstream transcription factors are typically activated by TLR signaling cascades?

$\text{Jun/Fos}$ and $\text{NFkB}$

According to the notes, how many blood cells does the bone marrow produce daily?

Around 500 billion new blood cells per day, or $2.4 \times 10^{6}$ per second.

What is the general functional distinction between myeloid and lymphoid cells?

Myeloid white blood cells generally provide innate protection, while lymphoid cells generate adaptive immunity.

What are the four primary clinical signs of local inflammation caused by immune activation?

Pain, redness, heat, and swelling (caused by the dilation of local blood vessels).

How does fever assist the immune response?

It inhibits pathogen proliferation and speeds up chemical reactions used by antimicrobial peptides and the complement cascade.

Distinguish between neutrophils and macrophages as described in the lecture.

Neutrophils are short-lived, abundant in blood, and make up most 'pus'; Macrophages are long-lived, 'professional' phagocytes abundant in areas like the airways and gut.

Which myeloid cell is specialized in attacking objects too large to engulf, such as parasitic worms?

Eosinophils

How do Dendritic Cells (DCs) link innate and adaptive immunity?

They phagocytose pathogens, cleave them into peptides, bind these peptides to MHC (Major Histocompatibility Complex) proteins, and migrate to lymphoid tissues to activate lymphocytes.

Where do B-cells and T-cells develop and mature?

B-cells develop in the bone marrow; T-cells develop/mature in the thymus.

Which lymphoid cells are considered part of the innate immune response and participate in early defense against tumors?

Natural Killer (NK) Cells

What are the three subtypes of T-cells and their functions?

1. Cytotoxic T-cells: Directly kill infected host cells. 2. Helper T-cells: Activate other immune cells by secreting cytokines. 3. Regulatory T-cells: Inhibit the function of helper and cytotoxic T-cells.

Explain the process of clonal expansion in adaptive immunity.

When an antigen is presented, dormant lymphocytes with binding affinity become activated, leading to their proliferation and differentiation into effector cells.

What is the significance of the 'lag phase' in secondary immunisation?

The lag after the second exposure is shorter and the response is stronger because subsequent encounters stimulate memory cells created during the first encounter.

What does the skin graft experiment with brown and white mice demonstrate about immune tolerance?

It shows that the adaptive immune system can 'learn' to accept foreign cells as 'self' if they are introduced to a newborn host.

What happens if a 'self' protein is removed from an adult animal and reintroduced after several months?

The host mounts an immune response to the protein, demonstrating that the immune system can 'forget' what it learned in utero.