Clinical Immunology and serology Practice MLIS-201 Prof. Dr. Ezzat M Hassan Immunology Dept., Med....
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Transcript of Clinical Immunology and serology Practice MLIS-201 Prof. Dr. Ezzat M Hassan Immunology Dept., Med....
Clinical Immunology and serology Practice
MLIS-201
Prof. Dr. Ezzat M HassanImmunology Dept.,Med. Res. Inst., Alex. Univ.
OutcomesBy the end of the lecture the students will be
able to• Recognize Structure of the immune system.• Enumerate the Cell Frequency of Different
Leukocytes in Blood of Healthy Individuals
Structure of the immune system
C ells O rgans
Im m un e sys tem
1-Cells of the Immune System
Cells of the Immune System
BasophilsNeutrophils
EosinophilsLangerhans &Macrophages
Kupffer cellsDendritic cells?
Monocytic
CytotoxicHelper
Suppressor
T-cells
Plasmacells
B-cells Dendriticcells?
Myeloid cells
~ 60% neutrophils (50% - 70%) ~ 3% eosinophils (>0% - 5%) ~ 0.5% basophils (>0% - 2%) ~ 5% monocytes (1% - 9%) ~ 30% lymphocytes (20% - 40%)
Cell Frequency of Different Leukocytes in Blood of Healthy Individuals
Myeloid LineageGranulocytes
Neutrophils Eosinophils Basophils
Monocytes MegakaryocytesErythrocytes (RBC)Dendritic cells (APC)
Macrophages
Platelets
Neutrophils60-70% of WBCsMulti-lobed nucleusGranulated cytoplasmLife span is 2-3daysProminent in inflammatory responseLeukocytosis is marker for infectious
processDead neutrophils make up a large
proportion of pus.Actively phagocytic
Eosinophils~2% of WBCsBi-lobed nucleusGranulated cytoplasmStains red with acid dye (eosin)Prominent in response to parasitic
infections Phagocytic
Basophils
<1% of WBCsLobed nucleusHeavily granulated cytoplasmStains blue with basic dye Prominent in allergic responsesNon-phagocyticSecrete allergic & inflammatory mediators
Monocytes and MacrophagesMonocytes:Large WBCsMonocytes are circulating precursors of Macrophages.MacrophagesFound in the organs, not the blood.Made in bone marrow as monocytesCalled macrophages once they reach organs.Long livedPhagocyticInitiate immune responses as they display antigens to
the lymphocytes (APC). Activated by cytokines and gamma interferonSecretes numerous immune response factors
Macrophages
Liver
Kuppfer cells
Skin
Denteritic cells
CNS
Microglia
Spleen,lung
Macrophages
Bifunctional
Phagocytosis
Antigen presentation
Mast Cells
Found in many different tissuesContains granules which release histaminePlay role in allergic reactions
Dendritic CellsHave long “dendrites”Major role as APCStimulated by innate responseHave constitutive MHC II expressionPhagocytic
APC INTERACTING WITH T CELL
T cell
APC
N K (N a tu ra l k ille r ce lls)
T -ce lls B -ce lls
L ym p h o id ce lls
Lymphoid Lineage
Lymphocyte ProductionLymphocytes are produced in:
lymphoid tissues (e.g., tonsils)lymphoid organs (e.g., spleen, thymus)Bone marrow
Make up 20–30% of circulating leukocytesMajority are stored in lymphoid organs, not
circulating (remember that only about 1% of your WBCs are in the blood)
Classes of Circulating Lymphocytes
T cells: thymus-dependentMake up 80% of circulating lymphocytes
B cells: bone–marrow derivedMake up 10–15% of circulating lymphocytes
NK cells: natural killer cellsMake up 5–10% of circulating lymphocytes
Lymphocytes1-T Lymphocytes
Mature in thymus Have T cell receptors (TCRs) Recognize Ag on cells onlyCELL-MEDIATED IMMUNE RESPONSE
T cell subclasses:1. Cytotoxic T cells
Attack cells infected by viruses & malignant cells2. Helper T cells
Stimulate function of T cells and B cells3. Suppressor T cells
Inhibit function of T cells and B cells4. Regulatory T cells
Regulate the functions other T cells5. Memomry T cells
For secondary immune responses
Lymphocytes2-B Lymphocytes
Mature in bone marrowHave membrane-bound Ab(~10,000 per cell)Go from “naive” to activated.Differentiate into plasma cells, which produce
and secrete antibodies (immunoglobins)HUMORAL IMMUNE RESPONSEPlasma cells are Ab secretors
~1-2 week life span
P la sm a ce lls B -m e m o ry
B - ce lls
Immunoglobulins -Long lived-2ry immune response
B cells
Natural Killer (NK) Cells Also called large granular lymphocytes Responsible for immunological surveillanceLack T and B cell markersLack Ag receptorsInvolved with Ab-dependent cell-mediated
cytotoxicity (ADCC)Attack:
foreign cellsvirus-infected cellscancer cells
Lymphocyte DistributionTissues maintain different T cell and B cell
populations:T Cells: high in blood, thymus, marrow, spleen,
othersB Cells: high in nodes, spleen, others
Lymphocytes wander through tissues, migrating throughout the body to defend peripheral tissues (T cells move faster than B)
Have long life span (4 years+, up to 30!)Retain their ability to divide, which is
essential to immune system function
Hi ! Take short rest!!
Bone m arrow
Thym us gland
Prim ary
Spleen Lym ph nodes
Secondary
M ALT
Tertiary
Organs of Im m une System
Lymphoid Organs & Tissuesspleen, thymus
gland, Lymph nodes and
tonsilsPeyer’s patches and
bits of lymphatic tissue scattered in connective tissue
Figure 20.5
Primary lymphoid organs
ThymusSecretes hormones (thymosin and thymopoietin) that
cause T lymphocytes to mature It functions strictly in T lymphocyte maturation It does not directly fight antigensLocated in mediastinumDeteriorates after pubertyDivided into 2 thymic lobesSepta divide lobes into smaller lobulesEach lobule contains:
a dense outer cortex of dividing T cells a pale central medulla
T cells: divide in the cortex migrate into medulla leave thymus by medullary blood vessels
Secondary lymphoid organs
& tissues
Lymphoid FunctionsLymphoid tissues and lymph nodes:
Distributed throughout body to monitor peripheral infections respond before infections reach vital organs of trunk Lymph nodules in mucosa Lymph nodes monitor plasma/interstitial fluid Spleen Monitor blood
SpleenStructure
Gross Largest single collection of lymphoid tissue in the body Ovoid organ in upper left quadrant of abdomen
Microscopic Compartmentalized
Red pulp White pulp
Periarticualr lymphoid sheath Site of Ag presentation
Major cell types: Lymphocytes Macrophages Dendritic cells RBCs
Functions of the Spleen Filters the blood like lymph nodes filter the
lymph Phagocytes in the spleen remove abnormal
blood cells and other blood components by phagocytosis
• Storage of iron and other RBC products for later use or elimination
• Initiation of immune responses by B cells and T cells in response to antigens in circulating blood
• Site of lymphocyte proliferation Stores RBC’s & platelets
Lymph NodesStructure
Gross Bean-shaped structures Drains major segments of lymphatic system
Microscopic Major cell types
Lymphocytes Macrophages Dendritic cells
Cortex/paracortex/medulla Follicles
Primary Secondary
Peripheral Lymph Node StructurePeripheral Lymph Node Structure
Distribution•cervical region• axillary region• inguinal region• pelvic cavity• abdominal cavity• thoracic cavity• supratrochlear region
Lymph NodesFunctions:Filter potentially harmful particles from lymph Immune surveillance by macrophages and
lymphocytes Areas of lymphocyte production &
proliferation1st line of response to antigensSecondary follicle (Germinal center) is site of
B cell proliferation & differentiationAfter Ag stimualtion lymphocyte numbers
increase by 50X in efferent lymphatic vessel (Lymphadenopathy)
Tertiary lymphoid tissues
TonsilsFollicular structureContains lymphocytes, macrophages, mast
cellsGerminal centers appear in response to AgProtective role in URI
Appendix
Associated with intestinesResponds to AgRole in GI immune response
Mucosa Associated Lymphoid Tissues (MALT)
Lymphoid tissues below epithelium (Peyer’s Patches)
Presence of B cellsAg presented through unique cell (M cell)Preferentially responds with IgA antibody
Next Lecture: Innate immunity
Write assay aboutMucosa Associated Lymphoid TissuesLymph NodesFunction of spleen
Assignment:Cell Frequency of Different Leukocytes in Blood of Healthy and diseased Individuals.