Adaptive Immunity Lecture Notes

Flashcards covering key concepts from Dr. Jennifer Marshall's lecture on Adaptive Immunity.

What is Innate Immunity?

Immunity you are born with, with a fixed number of preformed pathogen recognition receptors. Cells can increase in number, but receptors do not change.

What is Adaptive Immunity?

Adapts to completely new structures, has 2 key receptors that are extremely variable, and shows strong increases in cell number but only of antigen-specific clones.

What is a disadvantage of the Innate Immune System?

Fast, many cells, but may not be able to react to something new.

What is a disadvantage of the Adaptive Immune System?

Can react to anything and has immunological memory, but is slow.

Name some Innate Immune Cells.

Neutrophils, macrophages, eosinophils, NK cells, mast cells, and dendritic cells.

Name some Adaptive Immune Cells.

B Lymphocytes and T Lymphocytes (T helper cells and cytotoxic T cells).

What does a B Lymphocyte do?

B cell receptor (BCR) binds free antigen. Secreted BCR is antibody. B cells can bind pathogens and toxins directly.

What does a T Lymphocyte do?

T cell receptor (TCR) binds to antigens presented by cells. T lymphocytes recognize processed peptides on MHC.

What does the B cell receptor do?

Recognizes 3D shapes (in a molecular way) and binding to it activates the cell.

What are the two main classes of T cells?

Cytotoxic T cells (bind peptide on MHCI and induce cell death) and T helper cells (bind peptide on MHCII and activate other immune cells).

What does MHC Class I do?

Presents cytoplasmic proteins (e.g., viral protein) and is expressed by most body cells.

What does MHC Class II do?

Presents external phagocytosed proteins and is only expressed by phagocytic immune cells (dendritic cells, macrophages, B cells).

Where do B and T cells develop?

B cells develop in the bone marrow. T cell precursors also start in the bone marrow but migrate to the thymus to become T cells and produce their TCR.

How are millions of antigen receptor variants generated?

Random recombination of Variable, Diversity, and Joining genes generates millions of antigen receptor variants.

In summary, what do B and T lymphocytes do?

B cells see free antigen and produce antibodies. T cells see peptide-MHC and stimulate immune cells (T helper cells) or kill other cells (cytotoxic T cells).

What does antibody do?

Neutralization/Agglutination, opsonization, cellular activation via antibody receptors (Fc receptors), complement cascade initiation, and memory.

Name the differences in Affinity and avidity between the antibody classes IgM and IgG

IgM (pentameric, early produced, high avidity) and IgG (monomeric, produced after affinity maturation, good tissue penetrance and placental transfer).

How do dendritic cells activate T cells?

Dendritic cells transport antigens to lymph nodes to activate T cells. Activated T cells will stimulate antigen-specific B cells. B cells mature to plasma cells. Plasma cells produce antibodies over a long time.

What are the effectors of immunological memory?

Long-lived plasma cells producing high affinity antibody over many years and long-lived clones of memory T and B lymphocytes.

What is active vaccination?

Antigen is injected to induce the immune system to make its own antibodies.

What is passive vaccination?

Antibody produced in humans, animals, or by biotech with passive i.v. transfer.

What can Monoclonal antibody drugs do?

Antibodies can be highly specific for anything and activate the immune system via opsonization.

What is Adaptive Immunity composed of?

Lymphocytes (T&B cells), accessory cells, humoral effectors (antibody).

What are the Antigen receptors in Lymphocytes?

B cell receptor, T cell receptor, antibodies.

How is Affinity Affinity Maturation related to immune memory?

V-D-J recombination