Part 2 Flashcards
What is the primary function of the adaptive defense system?
Specific Defense system that protects against infectious agents and abnormal body cells
It amplifies the inflammatory response and activates complement and activates complement. MUST BE PRIMED.
What type of immunity involves lymphocytes producing antibodies?
Humoral (antibody-mediated) immunity. B cells.
Antibodies circulate in body fluids.
What are antibodies responsible for?
Bind targets, inactivating them temporarily and marking them for destruction
Destruction is carried out by phagocytes or complement.
What is cellular (cell-mediated) immunity?
Lymphocytes act against targets directly or indirectly. T cells.
It enhances inflammation, activates macrophages, and directs immune response.
Define antigens.
Substances that can mobilize adaptive defenses and provoke an immune response
They trigger the body’s adaptive defenses.
What are the two key features of immunogenicity?
- Stimulate proliferation of specific lymphocytes
- React with activated lymphocytes and antibodies
Immunogenicity is a characteristic of complete antigens.
What is a hapten?
(incomplete antigens)
Haptens cannot elicit an immune response on their own.
What are antigenic determinants?
Certain parts of an antigen that are immunogenic. Most naturally occuring antigens have a variety on their surfaces.
A single antigen can mobilize several lymphocyte populations and stimulate the formation of many kinds of antibodies.
What are self-antigens?
Protein molecules on the surface of cells that are not antigenic to self but antigenic to others in transfusions or grafts.
Example: major histocompatibility complex proteins. Each MHC protein has deep groove that holds a peptide, either self-antigen or foreign antigen. T lymphocytes can only bind antigens presented on the MHC proteins.
What role do T lymphocytes play in relation to MHC proteins?
T lymphocytes can only bind antigens presented on MHC proteins
MHC proteins hold either self-antigens or foreign antigens.
What are the three types of cells in the adaptive immune system?
- B lymphocytes (B cells)
- T lymphocytes (T cells)
- Antigen-presenting cells (APCs)
APCs include dendritic cells and macrophages.
Where do lymphocyte precursors originate?
Red bone marrow
Both B and T lymphocyte precursors originate here.
Where do T cells mature?
Thymus
B cells mature in the bone marrow.
What is immunocompetence?
The ability of lymphocytes to recognize specific antigens
It develops during the maturation process.
What happens during the antigen encounter and activation phase?
When a lymphocyte’s antigen receptors bind its antigen, that lymphocyte can be activated
This leads to proliferation and differentiation.
What occurs after activated lymphocytes proliferate?
They differentiate into effector cells and memory cells
Memory cells and effector T cells circulate continuously.
What is positive selection in T cell education?
T cells must recognize self major histocompatibility proteins (self-MHC)
Failure to recognize leads to apoptosis.
What is negative selection in T cell education?
T cells must not recognize self-antigens
Recognizing self-antigen leads to apoptosis, eliminating self-reactive T cells.
Nonself antigens
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Immunogenicity
Stimulate proliferation of specific lymphocytes
Reactivity
React with activate lymphocytes and antibodies released by immunogenic reactions
What are Antigen-Presenting Cells (APCs)?
Dendritic cells, macrophages, B cells. Do not respond to specific antigens. Present fragments of antigens to T cells for recognition.
