8-30 IMM Intro Flashcards
Primary organs/tissues and role
Bone Marrow and Thymus
Contain developing lymphocytes
Secondary organs/tissues and role
Spleen, Lymph Nodes, MALT (mucosal-associated lymphoid tissue)
(Contain more mature cells active in host defense)
Site of B Cell maturation
Bone Marrow
What is hematopoiesis and where does it occur?
The development of all blood cells from progenitor stem cells and it occurs in the bone marrow. As a person ages it occurs more in the flat bones (sternum, vertebrae, iliac, and ribs) than the long bones.
Thymus characteristics
Bi-lobed organ in upper anterior thorax, each lobe has outer cortex and inner medula. Observable in infants (sail sign) but involutes with age.
Site of T Cell maturation
Thymus
Spleen characteristics
Upper left quadrant of abdomen, two sections: white pulp and red pulp.
What is in the white pulp of the spleen?
Lymphocytes: T Cells near arterioles in the periarteriolar sheath, B Cells are more peripheral
Lymph Node Groups
Cervical, supraclavicular, axillary, mediastinal, supratrochlear, mesenteric, inguinal, femoral, popliteal
Site of drainage of cervical nodes
scalp, face, nasal cavity, pharynx
Site of drainage of axillary nodes
arm, chest wall, breast
Site of drainage of inguinal nodes
genitalia, buttocks, anus, abdominal wall, leg
Site of drainage of mediastinal nodes
mid-chest, upper abdomen, lungs
Site of drainage of mesenteric nodes
small and large intestine, upper rectum
What does MALT stand for and what is it?
Mucosal-Associated Lymphoid Tissue; aggregates of lymphocytes aggregated throughout the mucosal surfaces of the body
MALT 4 sub categories
GALT (Gut-associated), BALT (Bronchial/Trachael-associated), NALT (Nose-associated), VALT (Vulvovaginal-associated)
GALT includes what four anatomical features
Tonsils, adenoids, appendix, Peyer’s Patch
Lymph fluid contains what cells
White blood cells and plasma; no red blood cells
Main functions of the lymphatic system (3)
- collect/drain excess fluid from surrounding tissue and return to vascular system
- absorb fat from the vili of the small intestine
- be a conduit for immune cells to and through nodes and back to circulation
Two lymphatic drainage systems
1) Upper right of body -> right lymphatic duct -> right subclavian vein
2) Rest of body -> thoracic duct -> left subclavian vein
Contents of lymph fluid coming in and leaving nodes
Coming in: more phagocytic cells and antigens
Leaving: more immune cells and antibodies
Lymphedema definition
interstitial collection of lymph due to disruption of lymph flow
Primary vs Secondary lymphedema
Primary: associated with genetic or inherited conditions
Secondary: due to underlying disease or consequence of prior treatment (commonly malignancy or cancer treatment)
Filariasis
- secondary lymphedema
- due to infection of the nematode Wuchereria bancrofti
- infection is trasmitted via mosquitos, worms reside in lymphatic vessels or nodes in legs or scrotum
Filariasis diagnosis and treatment
Diagnosis: observation of microfilarie on blood smear from blood drawn at night
Treatment: Diethylcarbamazine citrate (DEC) a microfilaricidal that is active against the adult worm
Lymphangitis
Inflammation or infection or the lymph node - commonly due to streptococcus pyogenes
Chylothorax
accumulation of lymph in the thorax
Lymphadenopathy
enlargement (greater than 1 cm) of one or more lymph nodes
localized: 1 body area
generalized: 2 or more body areas
Lymphadenitis
Lymphadenopathy with pain and/or signs of inflammation
Lymphoma
Type of cancer of varied cells of the immune system
Three levels of defense against infection
1) intact skin and mucous membranes
2) innate arm of immune system
3) adaptive arm of immune system (cell-mediated and antibody-mediated (humoral) immunity)
Immune cells of innate response
- epithelial barriers
- phagocytic cells (neutrophils, macrophages, dendritic cells)
- cells that release inflammatory mediators (basophils, mast cells, eosinophils)
- natural killer cells
Immune cells of adaptive response
proliferation of antigen specific B and T cells
Neutrophil (type and function)
Type: WBC granulocyte
Function: engulf bacteria and fungi, oxidative burst
Monocyte/Macrophage (type and function)
Type: WBC mononuclear (monocytes mature to macrophages in tissues)
Function: engulf bacteria, fungi and cellular debris, produce cytokines, antigen processing
Eosinophil (type and function)
Type: WBC granulocyte
Function: allergic response and parasitic infection
Basophil (type and function)
Type: WBC granulocyte
Function: associated with hypersensitivity and release histamine
Mast Cell (type and function)
Type: Bone marrow derived cell
Function: granules contain vasoactive amines like histamine, proteases kill bacteria
Natural Killer (type and function)
Type: WBC lymphocyte
Function: recognizes stressed or infected cells and kills them by secreting macrophage-activating cytokine INF-gamma
Origin of follicular dendritic cells
Mesenchymal derived
Time frame when adaptive immunity begins to help
~ 12 hours
What is a cytokine?
Proteins produced and secreted by immune and non-immune cells that act as intercellular mediators to alter biological responses
Autocrine
Acts on the same cell that secretes it
Paracrine
Acts on adjacent or nearby cells
Endocrine
Acts on distant cells
What do cytokines do?
Bind to specific cytokine receptors expressed by target cells, typically inducing signal transduction (e.g. JAK-STAT pathway)
Cytokines of innate immunity
IL-1, IL-6, IL-12, IFN-a/IFN-b (Type I IFNs), IFN-g (Type II IFN), TNF-a
Cytokines of adaptive immunity
In Th-1 cells: IL-2, IL-3, IFN-g
In Th-2 cells: IL-4, IL-5, IL-6, IL-10, TGF-b
Cytokines of hematopoiesis
IL-3, IL-7, M-CSF, G-CSF, GM-CSF
What is a chemokine?
Specific type of cytokine (chemotactic cytokine) that causes cells to migrate towards a gradient of the chemokine
