What is the third line of defense?
Specific Immunity
How is specific immunity different from the first 2 lines of defense?
It is not innate, but adaptive. It is only acquired after an immunizing event such as an infection or immunization.
What is immunity?
The resistance developed after contracting childhood ailments that provides long-term protetion against future attacks.
What is immunocompetence?
The ability of the body to react with countless foreign substances.
What is an antigen/immunogen?
Molecules that stimulate a response by B and T cells. Usually protein or polysaccharide molecules on or inside all cells and viruses.
What 2 features most characterize the third line of defense?
Specificity and memory
What is the property of memory?
Refers to the rapid mobilization of lymphocytes that have been programmed to “recall” their first engagement with an invader and rush to attack if it becomes present again.
What are the 4 stages of specific immunity?
1) Lymphocyte development and differentiation
2) The Presentation of antigens
3) Challenge of B and T cell lymphocytes by antigens
4. 1) B-lymphocyte response: production and activites of anitbodies
4. 2) T-lymphocyte response: cell-mediatied immunity
Where do B cells mature?
Specialized bone marrow sites
Where do T cells mature?
In the thymus
What are antigen-presenting cells?
Macrophages or dendrites that process and present antigens to T cells in a lymphoid organ.
What are the 3 types of T cells and their functions?
1) helper- activate macrophages, assist B-cell processes and help activate cytotoxic T cells
2) regulatory- control T-cell response
3) cytotoxic- lead to the destruction of infected host cells and other “foreign” cells
Do T cells produce antibodies?
No
What are the main functions of cell markers/receptors?
1) attachment to nonself or foreign antigens
2) binding to cell surface receptors that indicate self (MHC molecules)
3) receiving and transmitting chemical messages to coordinate the response
4) aiding in cellular development
What is the MHC?
Major histocompatibility complex- a set of genes that code for human cell receptors, gives rise to a series of glycoproteins found on all cells except red blood cells, plays a vital role in recognition of self by the immune system and in rejection of foreign tissue.
What are the 3 types of MHC?
Class I
Class II
Class III
How do Class I MHC genes work?
They code for markers that appear on all nuclated cells =. They display unique characteristics of self and allow for the recognition of self molecules and regulation of immune reactions.
How do Class II MHC genes work?
They code for immune regulatory markers found on macrophages, dendritic cells, and B cells. They are involved in presenting antigens to T cells during cooperative immune reactions.
How do B cells mature?
They mature on certain bone marrow sites called stromal cells. These cells nurture stem cells and provide chemical signals that initiate B-cell development. Hundereds of millions of distinct B-cells are able to develop due to gene modification and selection.
How do T cells mature?
Their maturation and development of their specific receptors are directed by the thymus gland and its hormones.
What is a epitope?
The primary signal that a molecule is foreign. A difference in molecule shape on an antigen.
What are the steps of a B cell response?
1) Binding of epitope
2) Anitgen processing and presentation
3) B-cell/T-cell recognition and cooperation
4) B-cell activation
5) Clonal expansion
6) Regulatory B-cell activity
7) Antibody production and secretion
What is opsonization?
A processin which specific microorganisms of other particles are coated iwth specific antibodies so that they will be more readily recognized by phagocytes.
What are the outcomes of antigen-antibody interaction?
Agglutinazation
Neutralization
(also an antitoxin can be activaed which neutralizes bacterial exotoxins)