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Immune system
Lecture 2011
Immune system
 Innate - non-specific
 adaptive – specific
(no immunisation required)
(immunisation required)
o
o
o
o
o
o
physical barriers (skin,
mucosa, cilia)
biological barriers
(symbionts)
chemical barriers (pH,
mucus)
soluble factors (lysozyme,
interferons, proteins ac.ph.,
complement)
Cells: phagocytes,
granulocytes
(rapid answer, restrictive
flexibility, non-specific
reaction, no memory)
Cells: T - lymfocytes
(directly kill cells/ virusinfected, foreign cells,
microorganisms)
o B – lymfocytes
(produce)
o Antibodies
(delayed answer, high
flexibility, high specifity,
memory and immunity)
o
Organs and cells of immune system
 Bone marrow
 Thymus
 Tonsils and adenoids
 Lymph nodes
 Spleen
 Peyer´s patches
 Appendix
 Lymphatic vessels
Cells of immune system (effect)
 non-specific
 specific
 intracelullar killing macrophages
 B-lymphocytes
(mononuclear phagocyte
system)
 “activating macrophages“!
produce cytokins
 APC!
 neutrophils
 extracellular killing
 NK-cells (CD16, CD56),
 “large, granular lymfocytes“
 (perforins, apoptosis), not MHC
restricted
 eosinophils (granules with
cytotoxic proteins)
(receptor: Ig)
o T-lymphocytes
(receptor:TCR in complex with CD,
Ag split in peptide fragments in
complex with MHC presented
by APC
(Tc) MHC I+Ag
(TH) Ag +MHC II presenting by
APC
Cell origin: Hemocytoblast
(pluripotent stem cell)
Myeloid lineage
Erythrocytes
Plateletes
Granulocytes
Monocytes
Dendritic cells
Mast cells
Lymphoid lineage
B-lymphocytes
T-lymphocytes
NK-cells
Tissues and organs of immune
system
 cells: blood, lymph, lymphoid tissue
 lymphoid tissue: lymphoid nodules,MALT
 primary or central lymphoid organs:
thymus
bone marrow
 secondary or peripheral: encapsulated:
lymph nodes
spleen
 non-capsulated:
Peyer´s
patches
appendix
tonsils
Cells of immune system
LYMPHOCYTES
 Can exist without
contact with another
cells (cytokines!)
 Migrate through
tissues, blood and
lymph
 2kg in organism/ 23 grams in blood
Lymphocytes
organ
T-lymph %
B-lymph %
thymus
100
0
bone marrow
10
90
spleen
45
55
lymph nodes
60
40
blood
80
20
NK
Cells of immune system
Antigen presenting cells (APC)
 heterogenous group of cells
macrophages
dendritic cells
Langerhans´ cells (skin)
B-lymfocytes
M-cells (GIT)
Dendritic cells
 APC
 originate in bone marrow, progenitor c.
 precursors are seeded through the blood to (T-
regions) or to non-lymphoid organs (Langerhans
cc. in the skin)
 high ability to be attracted to sites of antigen
challenge and travel via lymph vessels to
peripheral organs, presenting Ag to T-lymph
(satelite lymph node, initiate immune response)
 X folicular dendritic cc – origin just in stroma
of nodes, not presenting Ag, but retain Ag/Ab in
membrane – B-lymph and i. memory
Thymus
 immature lymphocytes from bone marrow settled the
thymus pre- and postnatally, undergoing -terminal
differentiation and proliferation
 elimination 95% (apoptosis), negative selection and
positive selection
 cortex (blood-thymus barries) x medulla (postcapillary
venules – mature lymphocytes leave thymus to Tregions in peripheral organs)
 reticular epithelial stroma, reticular cells!
 Dual embryonic origin - endoderm (3rd pair of
pharyngeal pouches) + mesenchym (lymphocytes),
 Intensive growth till puberty
 Inborn defect: di George syndrom- thymus aplasia
Thymus
anatomy
 Superior and anterior
inferior mediastinum
 lobus dx. et sin.
 lobuli, cortex, medulla
 (lobuli thymici accessorii)
 weight at birth (12-14g)
Thymus – cortex (85% T-cells)
 epithelial cells – cortical (stromal cells)
 secretory granules,desmosomes,3D network,
 express MHC I, MHC II
 T-cells
double negative, proliferation,gene rearrangement
pre-TCR along with coreceptors CD4 and CD8
double positive (CD4 and CD8), positive selection( CD4 or
CD8)
macrophages negative selection, apoptotic T-cc
dendritic cells
corticomedullary venules (functional thymocytes
exit to circulation to T-regions

Thymus – medulla (25% T-cells)
 Fully matured T-cells (single positive)
 Epithelial cells
 Hassal´s corpuscles (onion –like structures,
degenerated cells
 Macrophages
 Dendritic cells
 NO blood-thymus barrier
Blood – thymus barrier
Cortical epithelial cells
 Basal lamina
 Basal lamina
 Endothelial cells


Macrophages
 Only
present in cortex
Thymus involution
 Gradual involution from puberty
 After 50th year, adipose tissue
Lymph node
 organs of lymphoid tissue in the course of
lymphatics
 filter of Ag (microorganisms, tumor cells)
coming in the lymph before its return to
blood circulation
 recirculation: lymphocytes return to node via
high endothelial venules
 reticular connective tissue stroma
 cortex (lymphatic nodules, B-lymph)
paracortex (T-lymph)
Lymph node
 Cortex:
Subcapsullary sinuses
 Lymphatic follicules
 Interfollicular sinuses

 Paracortex
 Medulla
Lymphatic cords
 Medullary sinuses

Spleen
 largest lymphoid tissue accumulation
 filter of Ag (microorganisms, tumor cells) that
penetrate blood, producing antibodies and
activated lymphocytes
 White pulp , PALS (T-lymph) + lymhatic
nodule (B-lymph)
 Marginal zone (between red and white pulp,
active macrophages)
 Red pulp – lymphatic cords of Billroth +
venous sinuses
Vascular supply
 Splenic artery
 Trabecular artery
 Central artery (surrounded by PALS)
 Penicilar artery (in red pulp)
 Venous sinuses
 Trabecular veins
 Splenic vein
Spleen – proliferation in germ
center of lymhatic follicle (PCNA)