Immune System, Cells, and Molecules Flashcards
organs and tissues divided into two groups based on role in cellular development and host defense
- primary
- secondary
another name for primary
- central
- regenerative
another name for secondary
- peripheral
primary composed of
- contain developing lymphocytes
- bone marrow, thymus
secondary composed of
- contain more mature cells active in host defense
- spleen, lymph nodes, MALT
MALT
- mucosal associated lymphoid tissues
MALT includes
- tonsils
- adenoid
- appendix
- Peyer’s patches in GI tract
bone marrow
- site of hematopoiesis
- also site of B cell maturation
hematopoiesis
- the development of all blood cells from progenitor stem cells
what happens as a person ages
- most hematopoiesis occurs in flat bones
- sternum
- vertebrae
- ileac
- ribs
thymus location
- bi-lobed organ in upper anterior thorax
thymus each lobe surrounded by
- capsule
thymus lobes divided
- into multiple lobules
- by fibrous septa
thymus each lobule consists of
- outer cortex
- inner medulla
how cells enter/leave thymus
- enter via blood
- exit via efferent lymphatic vessels or blood
thymus drains into
- mediastinal lymph nodes
- venous drainage
thymus and aging
- undergoes physiologic involution with aging
- difficult to locate by puberty
thymus function
- maturation and selection of T cells
spleen location
- large, vascular organ located in left upper quadrant of the abdomen
- under the diaphragm
spleen blood supply
- supplied by a single artery
- dividing into smaller branches/arterioles at the hilum
two sections of the spleen
- white pulp
- red pulp
white pulp
- contains lymphocytes
- T cells near arterioles in the periarteriolar sheath
- B cells are more peripheral in B cell ring or corona
red pulp
- involved with red blood cell breakdown
function of spleen
- major site of immune responses to pathogen and other foreign substances in the blood
structure of lymph nodes
- outer fibrous capsule
- multiple afferent lymphatic vessels
- one efferent lymphatic vessel (subcapsular sinus)
- three concentric regions
concentric regions of lymph nodes
- cortex (B cells)
- paracortex (T cells)
- medulla
cortex
- has cell aggregates called follicles
- may contain germinal centers
- where B cells are located
lymph nodes and foreign antigens
- often the first organized lymphoid structure to encounter foreign antigens
fluid from lymph node
- enriched with antibodies and more lymphocytes
cervical node location
- head and neck
cervical node site of drainage
- scalp
- face
- nasal cavity
- pharynx
axillary node location
- axilla
axillary node site of drainage
- arm
- chest wall
- breast
inguinal node location
- groin
inguinal node site of drainage
- genitalia
- buttock
- anus
- abdominal wall
- leg
mediastinal node location
- in/near mediastinum
- central posterior thorax
mediastinal node site of drainage
- mid-chest
- upper abdomen
- lungs
mesenteric node location
- lower abdomen
- near intestine
mesenteric node site of drainage
- small and large intestine
- upper rectum
MALT definition
- aggregates of lymphocytes found throughout mucosal surfaces in body
mucosal surfaces in body
- gastrointestinal
- respiratory
- urogenital
MALT divided into
- GALT
- BALT
- NALT
- VALT
GALT
- Gut associated lymphoid tissue
GALT includes
- tonsils
- adenoids
- appendix
- Peyer’s patches
BALT
- bronchial/tracheal-assocaited lymphoid tissue
NALT
- nose-associated lymphoid tissue
VALT
- vulvovaginal-associated lymphoid tissue
antibody producing plasma cells in MALT as compared to other tissues
- far exceeds number in the spleen, lymph nodes, and bone marrow combined
importance of MALT
provide crucial defense against pathogens encountering mucosal surfaces
lymph system contains
- white blood cells (leukocytes)
- plasma
- no red blood cells (erythrocytes)
structure of lymph system
- branching system with components in both both superficial and deep tissues
- NOT a circular system
- capillaries (smallest vessels) extend into tissues and eventually have closed ends
main functions of lymphatic system
- collect/drain excess fluid from surrounding tissues and return it to the vascular system
- absorb fat from the villi of the small intestine
- be a conduit for immune cells to travel through the nodes and back into circulation
lymphatic drainage initiated by
- interstitial fluid uptake in lymphatic capillaries
lymphatic drainage flow
- no pump (heart)
- flow by skeletal muscle contraction, arterial pulsation, unidirectional valves that prevent back flow
- smooth muscle in walls of larger vessels
- flow through multiple lymph nodes before entering circulation in the blood
lymph drainage systems
- 2 separate, asymmetric systems
right lymphatic duct collects from
- lymph from upper right areas of the body
- right side of head
- heart and lungs
right lymphatic duct drains into
- right subclavian vein
rest of body drains into
that duct drains into
- into thoracic duct
- then drains into left subclavian vein
what is in the lymph entering the lymph node
- phagocytic cells and antigens
initiation of immune response
- processing of foreign antigens
fluid exiting nodes
- exists with higher number of immune cells and antibodies
Virchow’s node
- node in the left supraclavicular region
- receives drainage from abdomen
enlarged node in Virchow’s node
- concerning for certain malignancies involving the abdomen or left chest
definition of lymphedema
- interstitial collection of lymph due to disruption of lymphatic flow
lymphedema
- usually progressive, can lead to tissue hypertrophy and fibrosis
- swelling, skin changes, pain, restricted range of motion, and non pitting edema
complications of lymphedema
- skin infections
- malignancy
- reduced quality of life including aspects of emotional, physical, and social well being
primary lymphedema
- associated with genetic or inherited conditions
- associated with lymphatic disruption
secondary lymphedema
- due to underlying disease or a consequence of prior treatment
- mostly due to malignancy or cancer therapy
secondary lymphedema etiology
- obstruction of lymphatic vessels or nodes (compression by a tumor)
- infiltration of the vessels by tumor cells
- most common in breast cancer
filariasis due to
- infection by the nematode Wuchereria boncrofti
- infection transmitted by mosquitos
standard method for diagnosing active filariasis
- blood draw at night when they are in peripheral blood
- serological enzyme alternate testing as well
main goal of treatment of filariasis
- to kill the worm
treatment for filariasis
- dethylcarbamazine citrate (DEC)
- microfilaricidal and active against adult worm
do we use DEC for lymphedema and elephantiasis
- no
- most people with lymphedema are not actively infected with the filarial parasite
lymphangitis
- inflammation or infection of the lymph vessels
lymphangitis site of infection
- site of infection distal to affected vessels
lymphangitis pathogen
- strep pyogenes
- Strep A
chylothorax
- accumulation of lymph in thorax
chylothorax due to
- severing thoracic duct during surgery
lymphadenopathy
- enlargement (<1 cm) of one or more lymph nodes
localized lymphadenopathy
- when present in only 1 body area
generalized lymphadenopathy
- when present in more than 2 body areas
lymphadenitis
- lymphadenopathy with pain and/or signs of inflammation
- usually associated with active infection
lymphoma
- malignancy of varied cells of the immune system
first line of defense against microorganisms
- intact skin and mucous membranes
second line of defense
- innate (natural) arm of immune system
- from 0-12 hours
highly specific protection provided by
- adaptive (acquired) immune system
- takes several days to become fully functional
- 1-7 days
two components of the adaptive arm
- cell mediated immunity
- antibody mediated (humoral) immunity
innate response uses
- epithelial barriers
- phagocytic cells
- cells that release inflammatory mediators
- natural killer cells
phagocytic cells
- neutrophils
- macrophages
- dendritic cells
cells that release inflammatory mediators
- basophils
- mast cells
- eosinophils
adaptive responses involve
- proliferation of antigen-specific B-and T-cells
when does the adaptive response occur
- when the surface receptor of these cells binds to an antigen
antigen-presenting cells
- display the antigen to lymphocytes
- collaborate with them in the response to the antigen
innate response immune cells
- neutrophil
- monocyte/macrophage
- eosinophil
- basophil
- natural killer
neutrophil type
- WBC granulocyte
neutrophil function
- engulf bacteria and fungi
- oxidative burst
monocyte/macrophage type
- WBC Mononuclear
monocyte/macrophage function
- engulf bacteria, fungi, and cellular debris
- produce cytokines
- antigen processing
eosinophil type
- WBC granulocyte
eosinophil function
- allergic response
- parasitic infection
basophil type
- WBC granulocyte
basophil response
- hypersensitivity
- release histamine
mast cell type
- bone marrow derived cell
mast cell function
- granules contain vasoactive amines like histamines
- proteases kill bacteria
natural killer cell type
- WBC lymphocyte
natural killer cell function
- recognizes stressed or infected cells and kills them by secreting macrophage-activating cytokine interferon gamma
adaptive response immune cells
- B cell
- T cell
B cells
- plasma cell
- memory cell
B cell type
- WBC Lymphocyte
B cell function
- specific recognition of antigens as mediator of HUMORAL immunity
T cells
- helper
- cytotoxic
- regulatory
- memory
T cell type
- WBC lymphocyte
T cell function
- specific recognition of antigens as mediator of CELL-MEDIATED immunity
B lymphocyte
- neutralization of microbe
- phagocytosis
- complement activation
Helper T lymphocyte
- activation of macrophages
- inflammation
- activation (proliferation and differentiation) of T and B lymphocytes
cytotoxic T lymphocyte
- killing of infected cell
regulatory T lymphocyte
- suppression of immune response
natural killer cell
- killing of infected cell
antigen presenting cells
- macrophage
- dendritic
- follicular dendritic
origin of macrophage
- bone marrow derived
functions of macrophage
- phagocytosis
- antigen presentation
- effector phase of CMI
locations of macrophage
- lymph nodes
- immune tissues
- immune organs
dendritic origin
- bone marrow derived
dendritic functions
- phagocytosis
- antigen presentation
- initiation of T-cell responses
dendritic locations
- lymph nodes
- immune tissues
- immune organs
follicular dendritic origin
- mesenchymal derived
follicular dendritic functions
- antigen presentation
- display of antigen to B cells in humoral immune response
follicular dendritic location
- lymph nodes
- spleen
- MALT
cytokines
- group of proteins produced and secrets by immune and non-immune cells
- act as intercellular mediators to alter biological response
autocrine
- cytokine acts on same cell that secretes it
paracrine
- acts on adjacent or nearby cell
endocrine
- acts at a distance to stimulate cells
autocrine cytokine example
- IL-2 produced by T cells
- aids in stimulation and proliferation of same cell
paracrine cytokine example
- A T cell engages a macrophage and secretes interferon gamma to activate the macrophage
endocrine cytokine example
- GM-CSF can be made by T cells at a site of infection
- if made in sufficient quantities it affects granulocyte production in bone marrow
cytokine receptors
- homodimers or heterodimers
- become phosphorylated and activate signaling molecules
JAK-STAT signaling pathway
- major pathway involved in immune regulation
- cytokine interacts with cytokine receptor, activates signaling molecule JAK, JAK activates other molecules such as STAT
- STAT is a transcription factor that moves into the nucleus, binds promoters, and induces gene transcription
- new proteins stimulate target cell action/function
JAK
- Janis Kinase
STAT
- Signal transducer and activator of transcription
Top pro inflammatory cytokines
- TNF-alpha
- IL-1
- IL-6
chemokines
- small chemo-attractant molecules that cause cells to migrate toward a concentration gradient of the membrane
what expresses chemokine receptors?
- the target
- responding cells
what does activation of the target receptor do?
- signals cytoskeleton rearrangement
- cell moves to areas with highest chemokine concentration
categories of chemokines based on
- position or arrangement of cysteine amino acids
4 caregories of chemokines
- CC
- CXC
- single C
- CXXXC
X is any other amino acid
CXCL8
- Important for recruitment of neutrophils
- CLEAN UP ON AISLE 8
CXCL2
- recruits naive T cells
- 2 TYPES OF 2 CELLS
CCL2
- helps activate and recruit macrophages
CCL2 HAS 3 LETTER
MAC IS SHORT FOR MACROPHAGE WHICH ALSO HAS 3 LETTERS
protease inhibitors
- enzymes that cleave proteins and breakdown inhibitors
alpha 2 macroglobulin
- helps prevent the dissemination of pathogens
defensins
- can penetrate microbial membranes
- destroy bacteria, fungi, and enveloped viruses
