Lymphocytes and Immunity Flashcards
What is the normal range for Lymphocytes in dogs?
1,000-4,500 / microliter
What is the normal range for Lymphocytes in cats?
1,500-7,000 / microliter
What line of defense are Lymphocytes associated with?
3rd line (specific immunity)
True or False: Lymphocytes are not capable of phagocytosis
true
True or False: Lymphocytes are capable of recirculation
True
What is the life span of Lymphocytes?
weeks to months to years
What is Lymphocytosis?
increase in lymphocytes
What are the causes of Lymphocytosis?
- epinephrine release (splenic contractions)
- leukemia/neoplasia
- antigenic stimulation
- chronic inflammation
- later stages of resolving infections
- very young animals
What types of Leukemia/Neoplasia cause Lymphocytosis?
- lymphoma
- lymphosarcoma
What is Lymphopenia?
decrease in lymphocytes
What are causes of Lymphopenia?
- stress response
- immunosuppressive drug therapy
- immunodeficency syndromes
- acute viral diseases
- decreased production (bone marrow)
What immunosuppressive drug causes Lymphopenia?
tacrolimus
What immunodeficency syndromes cause Lymphopenia?
- FIV
- CIV
- combined immunodeficency syndrome
What acute viral diseases cause Lymphopenia?
- FeLV (acute stage)
- parvovirus
Nucleus (Lymphocyte)
- round, oval
- non segmented
- mononuclear
- dark purple
Cytoplasm (Lymphocyte)
- light blue
- has a high N:C ratio
What is the size of a Small Lymphocyte?
7-9 microns
Cytoplasm (Small Lymphocyte)
- little to no cytoplasm
- may see faint cytoplasm
What is the size of a Large Lymphocyte?
9-11 microns
Cytoplasm (Large Lymphocyte)
more abundant
What is a Reactive Lymphocyte?
- currently being stimulated
- AKA: immunocytes, stimulated lymphocytes, activated lymphocytes
What is the size of a Reactive Lymphocyte?
15-20 microns
Nucleus (Reactive Lymphocyte)
- large
- dense chromatin
- chromocenters
Cytolplasm (Reactive Lymphocyte)
- abundant
- intense blue
Where are Atyplical Lymphocytes seen?
- infections
- neoplasia
Nucleus (Atypical Lymphocytes)
indented or clefted
Cytoplasm (Atypical Lymphocytes)
- irregular borders
- dark blue cytoplasmic granules (due to asynchronous development of nucleus and cytoplasm)
What is Lymphocytopoiesis?
production of lymphocytes
Maturation process of a T Cell
PPSC Lymphoid Stem Cell Pre T-Cell T-Lymphoblast T-Prolymphocyte T-Lymphocyte (T-Cell)
Maturation process of a B-Cell
PPSC Lymphoid Stem Cell Pre B-Cell B-Lymphoblast B-Prolymphocyte B-Lymphocyte (B-Cell)
Where does the T-Cell mature?
thymus
Where is the T-Cell stored?
spleen (white pulp)
lymph nodes
What is the T-Cell’s role in immunity?
- cell mediated immunity (in tissue)
- use cytokines
- enter circulation and travel to site in tissue where antigen entered
What % of T-Cells are in circulation?
70%
Where does the B-Cell mature?
- :”Bursa Equivalent”
- GALT: gut associated lymphoid tissue
- bone marrow
Where is the B-Cell stored?
- spleen
- lymph nodes
- tonsils
- other lymphoid tissue
What is the B-Cell’s role in immunity?
- humoral immunity (plasma)
- use antibodies
- rarely seen in circulation
What % of B-Cells are in circulation?
30%
Where do Natural Killer Cells mature?
bone marrow
Where are Natural Killer Cells stored?
- spleen
- lymph nodes
- tonsils
- lymphoid tissue
What is the Natural Killer Cell’s role in immunity?
- non specific immunity
- 2nd line of defense
- effective against “traitor” cells
- must come in direct contact with cell
- require no activation
What are Memory Cells?
- B or T Cells
- clones of the original lymphocyte
Where are Memory Cells stored?
survive in lymphoid tisse waiting for 2nd exposure to antigen that stimulated their formation
What are the parts of the Lymphatic System?
- lymphatic ducts and vessels
- lymphatic tissue
What are the 3 compartments of the Lymphatic Tissue?
- bone marrow (where all cells originate)
- central lymphoid tissue (where lymphocytes mature)
- peripheral lymphoid tissues (where cells are stored until needed)
What are Peripheral Lymphoid Tissues?
- bone marrow
- GALT
- spleen
- lymph nodes
- tonsils
What is Plasma?
fluid portion of blood that carries nutrients, electrolytes, proteins, sugars, hormones etc
What is Lymph?
-comes from plasma
-primarily composed of water, electrolytes and sugars
doens’t contain large proteins like plasma
What are the primary functions of the Lymphatic System?
- removal of excess tissue fluid
- waste material transport
- filtration of lymph
- protein transports
What things get filtered out of the Lymph?
- microorganisms
- cellular debris
- metabolic waste products
- any foreign matter or waste material
What proteins does the Lymphatic System transport?
-enzymes
-hormones
-other proteins
(carried from the tissue of origin into blood)
What are the Tissues and Organs of the Lymphatic System?
- lymph nodes
- spleen
- thymus
- tonsils
- GALT
Where is the Spleen located in the body?
- left side of abdomen
- near stomach
What are the 2 types of function of the Spleen?
- Hematologic
- Lymphatic
What are the Hematologic functions of the Spleen?
-blood storage
-removal of foreign material and debris
(occurs in the red pulp)
What are the Lymphatic functions of the Spleen?
-activation and cloning of lymphocytes
occurs in the white pulp
True or False: The spleen is not essential for life
True
What is the #1 reason for a Splenectomy?
rupture/trauma
What is the #2 reason for a Splenectomy?
splenic tumors
Where is the Thymus located?
mediastinum
Where are the Tonsils located?
- larynx
- pharynx
- intestine
- prepuce
- vagina
The Tonsils are similar to the Lymph Nodes EXCEPT:
- are found near mucosal surfaces
- located at beginning of lymphatic drainage
- have no capsule
The GALT makes up ?% of the….
- 25%
- small intestinal mucosa and submucosa (ileum)
What is the function of the Immune System?
protect the animal from anything that may cause disease or damage
How does the Immune System protect the animal?
recognizes “self” from “non self” and destroys “non self”
What is an Antigen?
any foreign substance (solid or liquid) that is capable of inducing a specific immune response
What is an Epitope?
uniquely shaped site on surface of antigen that is recognized by an antigen recptor
What determines the shape of the Epitope?
amino acid sequence
What is Pathogenicity?
ability of an anitgen to cause disease (how easy to get)
What is Virulence?
degree of pathogenicity that an antigen can cause (how sick you get)
What makes a “good” Antigen?
- virulence and pathogenicity
- size:bigger is better
- foreignness
- complexity and chemical stability
- dose (more=more pathogenic)
- root of administration
- host genetics or immune status
What is Non-Specific Immunity?
- “innate immunity”
- rapid or instantaneous in response
- generalized
What are the 2 type of Non Specific Immunity?
- first line of defense
- second line of defense
What are the types of First Line of Defense Immunity?
- physical barriers
- chemical barriers
What are the types of Physical Barriers?
- hair (coat)
- intact epithelium
- mucous membranes
- cilia
What are the types of Chemical Barriers?
- tears
- mucus
- saliva
- HCL acid
- normal flora
- sebum/sweat
What are the types of the Second Line of Defense Immunity?
- phagocytosis
- NK cells
- interferons
- complement
- inflammatory response
What cells can Phagocytize?
all WBCs except Lymphocytes
What are the steps of Phagocytosis?
- atraction
- attachment
- ingestion
- fusion
- digestion
What cells do NK cells attack?
traitor cells (cells infected with virus, or have become cancerous)
What is Perforin?
chemicals that NK cells release
creates holes in cell => lysis
What are Interferons?
produced by host cell that have been infected by a virus
have antiviral proteins
How do Interferons work>?
“interferes” with viral DNA/RNA replication and protein synthesis
responds rapidly to prevent further replication (~hrs)
What is Complement?
group of inactive enzymes in plasma
activated with formation of an antigen/antibody complex
How does Complement lyse an antigen?
- complement binding sites on antbody become exposed
- complement binds to each site and becomes activated
- once all sites are occupid, complement fixation occurs
- complement arranges in donut formation on antigen =>hole forms => lysis of antigen
What are the 5 signs of Inflammation?
redness pain swelling heat decreased loss of function
What is Inflammation?
body’s normal response to insult or injury
What is Infection?
proliferation in the body with microorganisms (bacteria, viruses, fungi, parasites etc. )
What is the purpose of Inflammation?
- limit the spread of pathogens and ultimately destroy them
- remove debris of damaged tissue
- initiate healing/repair of tissue
What is Step 1 of the Inflammatory Response?
Vasoconstriction
What happens during Vasoconstriction?
-prevents hemorrhage
-initiates coagulation (platelet plug forms)
(~5-10min)
What is Step 2 of the Inflammatory Response?
mast cell degranulation
What happens during Mast Cell Degranulation?
granules are released
Histamine
vasodilation and increased capillary permeability
Heparin
localized anticoagulant promotes blood flow to area RBCs=healing WBCs=defense PLTs=coagulation
Which of the 5 signs of Inflammation occurs during Step 2?
REDNESS
localized hyperemia
What is Step 3 of the Inflammatory Response?
fluid from plasma pours into area
What happens during Step 3?
enzymes, antibodies, complement, plasma proteins (clotting factors) into damaged tissues
Which of the 5 signs of the Inflammtory Response occurs during Step 3?
EDEMA —> impinges on nerve endings in tissue—-> PAIN—-> LOSS OF FUNCTION
What is Step 4 of the Inflammatory Response?
clot formation
What happens during Step 4?
wall off area adjacent to site of injury to prevent further spread of microbes
What is Step 5 of the Inflammatory Response?
neutrophils and macrophages inflitrate area
What happens during Step 5?
- removal of debris and pathogens (by phagocytosis)
- pyrogens (produced during phagocytosis)influence hypothalamus and produce pyrexia
Which of the 5 signs of Inflammation occurs during Step 5?
PAIN
HEAT
What are benefits to having Pyrexia?
- promotes interferon activity
- inhibit reproduction and replication of bacteria and viruses
- elevates metabolic rate to accelerate rate of tissue repair
What is Step 6 of the Inflammatory Response?
return to normality
What happens during the Return to Normality?
- histamine, heparin and other chemicals are diluted with influx of increased amount of fluid
- return to normal vessel diameter and fenestrations return to normal size
What are the 2 types of Specific Immunity?
cell mediated immunity
humoral immunity
What are the properties of Specific Immunity?
- initiated as a reaction to an epitope on the antigen
- response is unique and specifically aimed against the antigen
- memory cells are produced
What is Cell Mediated Immunity?
- product of Tcells
- takes place in tissue
- effective against intracellular pathogens
- activated by macrophages
Where do T cells become sensitized?
in the tissue
What are the 3 types of “Sensitized” T Cells?
- cytotoxic T cells
- helper T cells
- suppressive T cells
What are Cytotoxic T Cells?
(Tc)
(CD8)
(killer cells)
What is the function of Cytotoxic T Cells?
-attach directly to antigen (as presented by macrophage) and destroy:
How do Cytotoxic T Cells destroy antigens?
- release perforins
- lyphotoxins
- induce apoptosis
- known as “lethal hit”
What are Helper T Cells?
(Th)
CD4
What is the function of Helper T Cells?
secrete cytokines into surrounding tissues
What cytokines do Helper T Cells secrete into the tissue?
- interlukins
- macrophage migration factor
Helper T Cells (interlukins)
chemicals that stimulate and increase activation of B cells and other T cells
What is the function of Macrophage Migration Factor?
attracts, stimulates and entrapts macrophages
What are Suppressor T Cells?
(Ts)
What are the functions of Suppressor T Cells?
- inhibit helper and killer T cells and stop B cells from becoming plasma cells
- release cytokines that signal all cells involved to shut down the immune response
- negative feedback mechanism
What is Humoral Immunity?
- product of B cells
- GALT or Bone Marrow
- takes place in plasma against extracellular pathogens
What activates B Cells?
formation of antigen/antibody complex
What are the 3 steps of when an Antibody attaches to an Antigen?
- neutralization
- agglutination and preciptiation
- complement system is activated
Neutralization
all active sites of antigen are bound by antibodies
Agglutination and Precipitation
- big conglomeration of antibodies and antigens => agglutination
- particles too big for solution => precipitate out, macrophage => phagocytize
What are the 5 Antibodies?
IgG IgA IgM IgE IgD
What is IgG?
present in greatest quantity
makes up 75-80% of antibodies
When is IgG produced?
during first exposure to antigen
What is the production time of IgG?
slow
What other antibodies does IgG include?
newborn antibodies
What is IgA?
present in bodily fluids and secretions: mucus, saliva, tears, colostrum
prevents any disease that enters through mucosal surfaces
When is IgM produced?
during 2nd exposure to antigen
What is the production time of IgM?
fast
What does IgM assist with?
activation of complement
What is IgE?
associated with allergic responses
Where is IgE present?
on membrane of mast cells
What does IgE help to attract?
eosinophils
What is IgD?
function not well known
What is Passive Immunity?
borrowed
instant
short lived/temporary
no memory cells
What is Aquired Immunity?
owned
takes 2-3 weeks to develop
long lived
have memory cells
What is Natural Passive Immunity?
colostrum
transplancental
What is Artificial Passive Immunity?
injection with immune serum from another animal (tetanus, antitoxic, antivenom, rabies, botulism)
What is Natural Aquired Immunity?
disease (infected -> recovered)
What is Artificial Aquired Immunity?
vaccination (modified live, killed, live, recombinant)
