Test 1: Module 2 (Immune System) Flashcards
Immune system
the bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes ….. macrophages, lymphocytes including the B cells and T cells,
and antibodies.
Phases of the adaptive immune response
- Recognition phase: APC to Naive T and B lymphocytes (day 0)
- Clonal expansion and differentiation
- Amplification phase: Antibody producing cells and effector T lymphocytes (~7 days)
- Effector phase: Elimation of antigens, cell mediated immunity, humoral immunity (~7-14 days)
- Termination phase: Apoptosis (~14-30 days)
- Memory: Surviving memory cells (>30 days)
Antibodies
proteins produced by the body (predominantly plasma B cells) that helps fight foreign pathogens
They bind to antigens
Major functions of immunoglobulins/Antibodies
- Directly attack antigens, destroying or neutralizing them through the process of agglutination, precipitating the toxins out of solution, neutralizing antigenic substances, and lysing the organism’s cell wall
- Activate the complement system
- Activate anaphylaxis by releasing histamine in tissue and blood
- Stimulate antibody-mediated hypersensitivity
Antigens
Any substance foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (such as a protein) and that is capable of binding with a product (such as an antibody or T cell) of the immune response
Substance that is capable of stimulating an immune response,
specifically activating lymphocytes, which are the body’s infection-fighting white
blood cells.
MHC/HLA
Major Histocompatibility Complex: membrane proteins that function to present antigenic peptides for recognition by T cells.
- MHC proteins found in humans are known as human leukocyte
antigens (HLAs) - MHC I & MHC II
- All nucleated proteins present MHC I (self-antigens)
- Antigen presenting cells (APC) contain MHC II.
Granulocytes
Basophil
Neutrophil
Eosinophil
Apart of innate (non-specific) immune system
Antigen-presenting cells (APCs)
B lymphocyte - adaptive
Macrophage - innate
Dendritic cells - innate
Basophil and mast cell function
Release chemicals that mediate inflammation and allergic responses
Neutrophils function
Ingest and destroy invaders
Most abundant. Make up 50-70% of WBCs in blood.
Eosinophils function
Destroy invaders, particularly parasites
Monocytes and Macrophages function
Ingest and destroy invaders. Antigen presentation
Lymphocytes and Plasma cell function
Specific responses to invaders, including antibody production
Second most abundant. Make up 20-35% of WBCs in blood.
B and T lymphocytes, NKCs
APCs
Specific/Adaptive Immune System
Dendritic cell function
Recognize pathogens and activate other immune cells by antigen presentation.
Role of antigen-presenting cells in the innate immune system (Macrophage and Dendritic cells)
- Phagocytosis of enemy cell (antigen)
- Fusion of lysosome and phagosome
- Enzymes start to degrade enemy cell
- Enemy cell broken into small fragments
- Fragments of antigen presented on APC surface
- Leftover fragments released by exocytosis
Natural Killer Cells – Innate
Kills tumors & infected cells
* Need activating ligands
* And absence of inhibitory signal (MHC I)
T Helper cells
CD4
Naiive helper T cell binds to the antigen on an antigen presenting cell. The antigen is presented on the MHC class 2 complex
The T helper cell becomes activated and clonal proliferation and differentiation occurs. (The T helper cells “call for help”)
Cytotoxic T Cells
CD8
An infected cell presents an antigen on the MHC class 1 complex. The CTL (cytotoxic T cell) becomes activated.
The CTL releases perforin and granzymes that invade the infected cell and induce controlled destruction (apoptosis) of the infected cell.
Activation of T cells
- Antigen is taken into APC (macrophage, dendritic cell). The antigen is processed and presented on the surface of the APC, via the MHC class 2 complex.
- Helper T cell binds to the antigen on the APC and calls for help.
- Cytotoxic T cells bind to the antigen on the APC and become activated
- Activated cytotoxic T cells bind to infected cells that present the processed antigen on MHC class 1 complex.
- The cytotoxic T cells release granzymes and perforins for controlled cell death of the infected cell (apoptosis).