Immuno Lec 1

What is the immune system?

A network of cells, molecules, tissues and organs that enable responsiveness against pathogens and maintain homeostasis.

What are the eight keys to an effective immune system?

1. Multiple levels of protection (physical barriers, time)
   2. Complete coverage of the entire body
   3. Discriminate “healthy” from “sick”; “self” from “non-self”
   4. Ready responsiveness
   5. Diversity (pathogen detection, response)
   6. Communication between immune and non-immune cells
   7. Memory against infectious agents for fast subsequent response
   8. Self-limiting to restore homeostasis after the challenge is removed.

What does 'multiple levels of protection' mean as a key to an effective immune system?

The immune system has multiple levels of protection, including physical barriers and time.

What does complete coverage of the entire body mean as a key to an effective immune system?

The immune system provides complete coverage of the entire body.

What discrimination must an effective immune system make?

It must discriminate “healthy” from “sick” and “self” from “non-self”.

What does ready responsiveness mean?

The immune system must be ready to respond.

Why is diversity important to an effective immune system?

For pathogen detection and response.

Why is communication between immune and non-immune cells important?

Communication between immune and non-immune cells is one of the keys to an effective immune system.

Why is memory important to an effective immune system?

Memory against infectious agents allows a fast subsequent response.

Why must immune responses be self-limiting?

To restore homeostasis after the challenge is removed.

What are leukocytes?

Immune cells that differentiate from hematopoietic stem cells in the bone marrow into two main lineages: myeloid or lymphoid.

Where do leukocytes differentiate?

From hematopoietic stem cells in the bone marrow.

What are the two main leukocyte lineages?

Myeloid and lymphoid.

What happens to T lymphocytes during development?

T lymphocytes migrate to the thymus for further maturation.

What is the overall organization of immune-cell development?

Immune responses are mediated by a network of cells with specialized function and restrictive developmental programs.

Where does additional immune-cell differentiation and maturation occur?

In peripheral lymphoid and nonlymphoid tissues; additional differentiation, maturation and activation-induced differentiation occurs in the periphery.

What are lymphoid organs?

Specialized organs in which immune cell development, differentiation, activation and functions are performed.

What are the two broad categories of lymphoid organs/tissues?

Primary lymphoid tissues and secondary lymphoid tissues.

What are primary lymphoid tissues?

Sites of leukocyte development.

What are examples of primary lymphoid tissues?

Thymus and bone marrow.

What are secondary lymphoid tissues?

Sites of lymphocyte activation.

What are examples of secondary lymphoid tissues?

Lymph nodes, spleen, and various mucosal associated lymphoid tissues (MALT).

What is MALT?

Mucosal associated lymphoid tissues.

What are the innate and adaptive arms of the immune system?

The immune system has innate and adaptive arms, which differ in specificity, diversity, induction, memory, mediators, and cells.

What is the specificity of the innate immune system?

For molecules shared by groups of related microbes and molecules produced by damaged host cells, e.g. pathogen associated molecular patterns (PAMP).

What is the specificity of the adaptive immune system?

For microbial and nonmicrobial antigens.

What are PAMPs?

Pathogen associated molecular patterns: molecules shared by groups of related microbes that are recognized by the innate immune system.

What is the diversity of the innate immune system?

Limited; receptors are germline encoded pattern-recognition receptors (PRR).

What is the diversity of the adaptive immune system?

Very large; receptors are produced by somatic recombination of gene segments.

What are PRRs?

Pattern-recognition receptors; the lecture describes innate immune receptors as limited in diversity and germline encoded.

How quickly is the innate immune response induced?

Rapidly, within hours and days.

How quickly is the adaptive immune response induced?

Slowly, over several days.

How do innate and adaptive immunity compare in self vs non-self discrimination?

Both innate and adaptive immunity discriminate self from non-self.

How do innate and adaptive immunity compare in memory?

Innate immunity has none; adaptive immunity has memory.

What are the mediators of innate immunity listed in the lecture?

Skin, mucosal epithelia, and antimicrobial molecules.

What are the mediators of adaptive immunity listed in the lecture?

Lymphocytes in epithelia and antibodies secreted at epithelial surfaces.

What cells are listed as components of innate immunity?

Macrophages, monocytes, granulocytes, NK cells, NKT cells, and ILC.

What cells are listed as components of adaptive immunity?

Lymphocytes (B and T cells).

What are the major differences between innate and adaptive immunity?

Innate: specificity for shared microbial/damage-associated molecules; limited germline-encoded PRR diversity; rapid induction; self/non-self discrimination; no memory; mediators include skin, mucosal epithelia and antimicrobial molecules; cells include macrophages, monocytes, granulocytes, NK cells, NKT cells and ILC.

Adaptive: specificity for microbial and nonmicrobial antigens; very large receptor diversity from somatic recombination; slower induction over several days; self/non-self discrimination; memory; mediators include lymphocytes in epithelia and antibodies at epithelial surfaces; cells are B and T lymphocytes.

What immune cells are listed as cellular players in an immune response?

Macrophages, neutrophils, basophils, eosinophils, mast cells, monocytes, dendritic cells, NK cells, NKT cells, T cells, and B cells.

Which granulocyte cell types are listed?

Neutrophils, basophils, and eosinophils.

Which lymphocyte cell types are explicitly listed as cellular players?

T cells, B cells, NK cells, and NKT cells.

Which other immune cells are listed besides lymphocytes and granulocytes?

Macrophages, monocytes, mast cells, and dendritic cells.

What is immunological memory?

The capacity of the immune response to generate a memory response to an antigen, allowing a faster subsequent response.

What is the purpose of vaccines according to the lecture?

Vaccines are designed to induce a primary response, and hence immunological memory, without causing disease.

What does the immunological-memory diagram illustrate?

A memory response to antigen A.

What does the lecture state about the phases of immune responses?

Immune responses go through multiple phas