What is an antigen?
-A foreign substance that can cause an immune response
What is an epitope?
- immunologically active site on antigen
- interacts with antibody
What are major histocompatibility complex molecules? (MHC)
- Self-ID models. Unique for individuals
- Class 1: found on all nucleated molecules (not platelets or RBCs)
- Class 2: found on macrophages and B lymphocytes.
What are the first and second line non specific immune responses?
- Skin and mucous
- inflammatory response (vasodilation, capillary leakiness, chemotaxis, phagocytosis)
What are opsonins?
Molecules that bind to foreign cells to make them more easily eaten by phagocytic cells
What is complement?
A group of immune proteins in blood
What happens when complement is activated?
- Membrane Attack Complex Forms
- Inflammatory response increases
- Acts as opsoninizing agent, enhances phagocytosis
What are other nonspecific mechanisms of immune response?
IFN a fibroblasts and IFN b leukocytes which both inhibit viral replication.
What do NK cells do?
-Kills non-specifically but requires part of the specific immune response to pull off.
What is required for a specific immune response?
-specific recognition of an antigen
What is an antibody mediated/humoral immune response?
-Attacks bacteria or extracellular viruses
What is a cell mediated immune response?
-Attacks intracellular viruses and cancer cells, which are self cells gone bad.
Where are antibodies found?
- The surface of B lymphocytes, where they function as receptors
- solubly circulate in the plasma.
What are the 5 types of antibodies?
- IgA
- IgD
- IgE
- IgG
- IgM
Describe IgA?
- 15% of antibodies
- Found in secretions
- Protect against bacteria on mucus membranes
Describe IgD?
- 0.2% of antibodies
- Found on surface of B lymphocytes. Help mature B lymphocytes.
Describe IgE?
.004%
- only in mammals
- Can trigger very powerful responses.
- Binds mast cells and basophils
- involved in parasitic info, allergens, hypersensitive reactions
Describe IgG?
- 75%, most abundant.
- can cross placenta to defend fetus
- activates complement
- binds to macrophages.
Describe IgM?
- 10%
- Acts against A and B RBC antigens.
- Activates complement.
What is the sequence of events in an antibody mediated immune response?
- Pathogen enters bearing antigen
- Antibody bearing B-lymphocyte recognizes and binds to antigen
- Macrophages phagocytize antigen and it’s MHC is displayed on surface after processing.
- Helper T cell goes after this MHC.
- This releases cytokines, which draw in more T cells and leads to proliferation of B cells.
- Plasma cells are differentiated
- Memory cells are differentiated (remember antigens and lead to response of T cells upon second mee
What is the sequence of events in a cell mediated immune response?
???
Define immunodeficiency
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Discuss B cell deficiencies
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Discuss T cell deficiencies
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