Lect 33 - linking innate and adaptive immunity

Flashcards from Lecture 33 about linking innate and adaptive immunity.

Immune cell communication methods

Soluble molecules binding to receptors on a cell membrane.

Cytokine binding to cytokine receptor

Sends a signal to the nucleus resulting in an increase and/or decrease in gene expression.

Chemokine binding to chemokine receptor

Sends a signal to the nucleus resulting in an increase and/or decrease in gene expression, activating molecules that direct cell movement.

Cell surface-bound receptors binding to cell surface-bound ligand

Alters the function of one or both cells.

Antigen

Anything that has the potential to be recognised by the immune system.

Foreign antigen

Anything from the ‘outside’ (transplants, pathogens, some chemicals).

Self-antigen

Immune system usually tolerant of self-antigen; if not tolerant, can result in auto-immune disease where immune system attacks self-antigen.

Activated dendritic communication with T cells

• Make cytokines that bind to receptors on T cell membranes,

• have cell surface-bound receptors that bind to T cell surface-bound ligand,

• present antigen to cell surface-bound receptors on T cells;

• leads to the activation of the T cell.

Major Histocompatibility Complex (MHC)

• Show a piece of microbe/pathogen to the T cell;

• T cells require this to be activated.

MHC-I

• Presents endogenous (intracellular) antigen;

• expressed on all nucleated cells.

MHC-II

• Presents exogenous (extracellular) antigen;

• expressed only on antigen presenting cells such as dendritic cells, macrophages, B cells.

Cytokines

Molecules such as interleukins and interferons that control growth and activity of immune cells.

Interleukins

• Produced by white blood cells, mainly T cells and macrophages,

• regulate immune cell communication and activation.

Interferons

• Produced by virus infected cells, immune cells, like dendritic cells and macrophages,

• defend against viruses and activate other immune responses.

Chemokines

Molecules that stimulate cell migration; cells need to migrate to site of inflammation.

Helper T cells activating B cells

• T cells that have been activated by a dendritic cell can help activate B cells;

• communication leads to activation of the B cell, and helps the B cell to make antibodies.

Complement activating B cells

• Antibody binding to a pathogen can trigger the classical pathway of a complement activation;

• fragments that are bound to antigen can also help activate B cells to make antibodies.

Immune response if stepping on a nail

1. Stand on nail, breaking the physical barrier (skin)

2. Pathogens (eg bacteria) enter the body

3. Chemical mediators lead to vasodilation and entry of phagocytic cells to the tissue to “eat and destroy” 

4. The complement pathway is triggered

5. Dendritic cells in the skin become activated through recognition of pathogen associated molecular patterns

6. Dendritic cells move to the local lymph node

7. Activated dendritic cells activate T cells via MHC

8. Antigen + T cells and complement activate B cells

9. B cells produce antibody

10. Complement, phagocytosis and antibodies help clear the pathogen