IMMUNE 3 Flashcards
what are antigenic determinants
specific part of antigen thats immunogenic where free antibodies or lymphocyte receptor binds
how many antigenic determents do most antigens have
hundreds; plastics have few determinants
what does the vast amount of antigenic determinants result in single antigens doing
Single antigen may mobilize several lymphocyte populations and/or stimulate production of many kinds of antibodies
what are major histocompatibility proteins, MHCs?
self-antigens that dot the external surface of all cells
what happens with MHCs in other individuals?
Strongly antigenic in other individuals (transfusion reactions, graph or organ rejection)
who are the key players in adaptive defense
lymphocytes - T lymphocytes and B lymphocytes and antigen-presenting cells
what are T lymphs part of
cellular immunity; attack infected cells
what are B lymphs part of
humoral immunity; antibodies
what does immunocompetent mean
recognize one specific antigen
what does self-tolerant mean
recognize self-antigens and don’t attack
what are antigen-presenting cells and what do they do
Macrophages, dendritic cells
- Engulf antigens, present antigen fragments on their cell surface as signals for T cells
what are the primary targets of B cells
extracellular pathogens, like bacteria, fungi, parasites, some viruses in extracellular fluid
what are the primary targets of T cells
intracellular pathogens (virus-infected cells) and cancer cells
where do both t and B cells originate
red bone marrow
where do t and B cells mature
b = red bone marrow
t = thymus
what are B cell effector cells
plasma cells
what are T cell effector cells
cytotoxic T cells, helper T cells, regulatory t cells
do both t and B cells create memory cells
yes
what are T cells activated by
antigen presenting cells (APCs)
how are T cells activated by APCs
T cell antigen receptors bind antigen-MHC complex ad to co-stimulatory signals on APC surface
whats the primary response of T cells to APCs
T cells proliferate into either helper T cells, cytotoxic T cells, or regulatory t cells
what are helper t cells
activate B cells, amplify innate defenses
what are cytotoxic T cells
directly attack/kill other cells
what are regulatory T cels
dampen immune response n areas where you dont want T cells seeking and destroying (prevent autoimmune reaction)
when does the primary T cell response peak
in a week
whats the secondary T cell response
memory cells;some t cells become memory cells; stay
inn system afer pathogen, so if pathogen comes back,
you can lead an attack against pathogen much quicker
what is activated in humoral immunity
native, immunocompetent B cells
how are B cells activated
Matching antigen binds to surface receptors
whats the primary response of B cells
B cells proliferate into plasma cells (effector B cells)
what do plasma cells / effector B cells secrete
large number of antibodies
whats the lag time from antigen challenge
3-6 days
when do B cell antibody levels peak
in 10 days
whats the secondary response of B cells
» Memory cells: long lived cells that can mount a response in the future
» Subsequent exposure leads to faster response
» Antibody levels peak in 2 – 3 days
how does the antigen/antibody complex inactivate invaders
neutralization, agglutination (cell-bound antigens), and precipitation (soluble antigens)
what do neutralization, agglutination (cell-bound antigens), and precipitation (soluble antigens) enhance
phagocytosis
what do precipitation (soluble antigens) enhance
inflammation
what does the antigen-anntiboody complex trigger
complement activation, which enhances inflammation and leads to cell lysis
what are two examples of active humoral immunity
naturally acquired; artificially acquired (vaccine)
what are two examples of passive humoral immunity
naturally acquired (mother passed to fetus via placenta or milk); artificially acquired (injection of exogenous antibodies)
describe B cells in active humoral immunity
encounter antigen and produce antibodies
describe B cells in passive humoral immunity
ready-made antibodies introduced to the body
