lect 3 - adaptive immune system

adaptive immune responses are different than

acquired responses

2 key features of adaptive immune responses

specificity and memory

specificity is a tailored response

increased effectiveness

2 things that memory provide

faster response and a more robust response

2 types of lymphocytes that carry out adaptive immune responses

B cells and T cells

antigen-presenting cells that are involved in adaptive immunity

monocytes, dedocytes

monocytes turn into

macrophages

dendritic cells are also called

professional APCs

b lymphocytes mature in

bone marrow or bursa of fabricius

t lymphocytes mature in

thymus

once activated, b lymphocytes become

plasma cells

once activated, t lymphocytes become

cytotoxic t cells or helper t cells

mature lymphocyte

a lymphocyte that is fully developed and capable of being activated

naive lymphocyte

a lymphocyte that has not yet encountered the specific antigen it will bind

lymphocytes can be

mature and still be naive

lymphocytes are generated in, mature in, activate in, perform effector fxns in

lymphoid organs

2 types of primary lymphoid organs

bone marrow, thymus

3 types of secondary lymphoid organs

spleen, lymphatics/LN, MALT

primary lymphoid organs are where

lymphocytes are formed and mature

primary lymphoid organs are where B and T cells

acquire their specific antigen receptor

primary lymphoid organs screen both B and T cells to

prevent attack of self-antigens

secondary lymphoid organs are where

mature lymphocytes are maintained

secondary lymphoid organs initiate

adaptive immune responses

lymphocytes perform most of their effector fxns or work in

secondary lymphoid organs

hematopoietic stem cells in the bone marrow give rise to

all blood cells

bone marrow is found in

medulla of long bones, some irregular bones

yellow marrow is found in

fat

red marrow is where

hematopoiesis and lymphocytes are generated

generation of lymphocytes

pluripotent stem cells of the bone marrow differentiate into immune and other cells during hematopoiesis

lymphocytes have specialized

surface receptors that recognize specific foreign proteins (antigens)

b lymphocytes have what recepors

b cell receptors (BCRs)

antigens that bind to BCRs do not

need to be processed intracellularly

T lymphocytes have

t cell receptors (TCRs)

antigens that bind to TCRs have been

processed inside a cell and displayed by very important cell surface proteins (MHC)

b cells develop in

bone marrow, and perform their fxns in secondary lymphoid organs

during b cell maturation, it must develop

a functional b cell receptor

when b cells move to secondary lymphoid organs, they are

mature but still naive

during maturation, b cells generate

a functional b cell receptor

BCRs are

cell-surface receptors

BCRs are connected to

other receptors as part of a co-receptor complex

BCR recognizes and responds to

non-self antigen

b cells recognize

native (unprocessed) antigen via BCR

activation of b cells leads to

clonal expansion and development of antibody-producing plasma cells

clonal expansion is when

daughter cells have same BCR as parent

mature and activated B cells become

effector cells called plasma cells that produce antibody

t cell life cycle

exit bone marrow, travel to thymus, travel to secondary lymphoid organs

t cells exit the thymus as

naive, mature t cells

in secondary lymphoid organs, T cells participate in

immune responses and become effector T cells

lymphoid progenitors (thymocytes) from the bone marrow seed

thymic cortex

immature thymocytes interact w/

epithelial cells in cortex

t cells mature as they move

toward the thymus medulla, interacting w/medullary epithelial cells, macrophages, dendritic cells

TCRs are

cell-surface receptors

TCRs are connected to other

receptors as part of a co-receptor complex

TCRs helps

immune system distinguish btwn self and non-self

TCRs recognize and respond to

non-self antigen

t cells recognize

linear peptides that have been processed intracellularly presented by antigen presenting cells (APCs) and other cells

T cells bind antigen and undergo

clonal expansion

TCRs bind to processed antigens that are

displayed by a major histocompatibility complex (MHC)

cells presents antigen to T cell via

MHC

MHC molecules are

class 1 and class 2

MHC molecules differ by where the

antigen they display was processed inside the cell

humoral cells are

b cells

cell-mediated cells are

t cells

cell-mediated immunity is carried out by

t lymphocytes

cell-mediated immunity targets

intracellular pathogens

CD8 cytotoxic T cells directly

kill infected cells

CD4 helper T cells produce

cytokines, activate humoral immunity and innate/immune cells

humoral immunity target

extracellular bacteria, toxin, viruses

humoral immunity cells produce

antibodies that can help destroy pathogens

lymph nodes screen

lymph/peripheral tissues

spleen screens

blood

MALT monitors

mucosal tissues

lymph nodes are designed for

maximal exposure of T and C cells to antigen

lymphatic fluid carries in

antigen, pathogens, debris, toxins

dendritic cells bring

antigen to the lymph nodes thruout lymphatics or blood vessels

blood delivers

b and t cells

afferent lymphatic vessel bring

lymph into the lymph node

macrophages/dendritic cells can find

antigen while filtering in thru marginal, medullary sinuses

t cells in paracortical region communicate with

macrophages/dendritic cells in medulla, B cells in cortex

primary follicles in cortical region are

b cells, mostly naive

secondary follicles (germinal centers) are

active follicles, B cells responding to antigen and differentiating

plasma cells in medullary sinus

antibodies constantly released

spleen mounts

immune responses to blood borne pathogens

resident macrophages in spleen

help recycle senescent RBCs

2 parts of spleen

red pulp, white pulp

red pulp is where

RBCs and macrophages are found, where the bulk of RBC recycling occurs

white pulp is the

lymphoid tissue that surround arterioles

white pulp structures are similar to

those found in LNs

3 parts of white pulp organization

periarterial lymphoid sheath (PALS), primary and secondary follicles (B cells), marginal zone

periarterial lymphoid sheath (PALS) consist mostly of

T cells and surround arterioles

primary and secondary follicles (B cells) are near

the PALS

marginal zone contains

B cells and is an area where the particular antigen gets trapped at the interface btwn red and white pulp

types of MALTs

NALT, BALT, GALT, urethral, vaginal lymphoid tissues

NALTs are

nasopharyngeal associated lymphoid tissue

NALTS contain

tonsils

BALTs are

bronchus associated lymphoid tissue

BALTs contain

lungs

GALTs are

gut associated lymphoid tissue

GALTs contain

peyer’s patches in small intestines, cecal tonsils of birds

all mucosa contain

specialized lymphoid aggregates that monitor/respond to potential pathogens