Download 3.Lecture 5- Resistance of the Body to infection

Blood Physiology
Professor A.M.A Abdel Gader
MD, PhD, FRCP (Lond., Edin), FRSH (London)
Professor of Physiology,
College of Medicine & King Khalid University Hospital
King Saud University
Riyadh
Hematopoiesis
Monocyte-macrophage system
Reticulo-endothelial System
Reticuloendothelial System-RES
Blood Monocyte
Tissue macrophage
Attached (fixed)
Mobile
Function is phagocytosis of:
•
•
•
•
Bacteria
Viruses
Dead tissues
Foriegn particles
Immune function
Reticuloendothelial System-RES
• RES is widespread in the body
Cells of the RES:
– Monocytes (blood macrophages)
– Mobile and fixed tissue Macrophages
– Specialiazed endothelial cells in bone marrow,
lymph nodes and spleen
– Reticular cells of lymph nodes spleen & bone
marrow.
Reticuloendothelial System-RES
Cells of the RES - Distribution:
• Tissue Macrophages in skin SC tissues
• Tisssue Macrophages of lymph nodes
• Tissue macrophages in lungs
• Macrphages (kupffer cells) in the
liver
• Macrphages in the spleen and bone
marrow
Reticuloendothelial System-RES
Blood Monocyte
Tissue macrophage
Attached (fixed)
Mobile
Function is phagocytosis of:
•
•
•
•
Bacteria
Viruses
Dead tissues
Foriegn particles
Immune function
34
Lecture # 5
Resistance of the Body to
infection
Immunity & Allergy
Lecture # 5
•
•
•
•
•
•
Immunity-Definition
Antigens
Immune Cells (b- & T- Lymphocytes)
Antibodies and B-Lymphocytes
Cellular Immunity
Clinical Application
Immunity?
The ability of the body to resist
damage (caused by micro-organisms, toxins etc)
• Immune system act to maintain health
(i.e. homoestatic)
• Immunological defenses act against:
– foreign organisms e.g. bacteria, viruses
– transplanted tissue or organs
Immunity -- Types
1. Acquired immunity:
–
–
the result of attack by bacteria, viruses etc
e.g. Vaccination
Long lasting (Memory)
2. Innate immunity
Non-specific: Examples:
• Ingestion of invading organisms (phagocytosis)
• Stomach acidity
• Skin barrier
• Lysozyme
• Natural killer lymphocytes
Immunity --
Types
Acquired immunity:
•
•
Specific against individual bacteria, virus,
toxin, foreign tissues
Basic types of acquired immunity:
Humoral immunity
Cell-mediated immunity
B-LYMPHOCYTES
Antibodies
Activated T-LYMPHOCYTES
(B-cell immunity)
(T-cell immunity)
Initiated by antigens
Immunity -- Types
1. Acquired immunity
2. innate immunity
–
–
–
Non-specific ingestion of invading
organisms
No memory cells
Phagocytic cells
•
•
Neutrophils
macrophages
Antigens
Antigens
Antigens:
• Specific chemical compounds (proteins,
polysaccharides) that initiate acquired
immunity
• High mol. weight (>8000)
• Antigenicity due to presence of
characteristic epitopes (molecular
groups) on its surface
Antigens
• If mol. Wt <8000 (Haptens), such
molecules rarely act as antigens.
• Haptens can act as antigens if they
combine with a protein and the haptenprotein complex can initiate an immune
response
• Antigens Recognized either directly by
lymphocyte or after being processed by
macrophages
The bases of
Acquired Immunity
are Lymphocytes
Immune cells
Two types:
– B-Lymphocytes
(Thymus independent, B-lymphocytes)
Produce antibodies
(Humoral Immunity)
2. T- lymphocytes
(Thymus dependent, T-lymphocytes)
Cellular mechanisms
(Cellular Immunity)
Hemopoiesis
(17.9)
Lymphocytes
Lymphopoiesis
–
cont.
Stem cell
(thymus, lymphoid tissue & bone marrow)
lymphoblast
intermediate pyronophilic blast cells
lymphocytes
B- Lymphocytes
(thymus-independents)
Found in:
• Bone marrow, germinal layer of
lymph node, red pulp of spleen
• Life span: 2-7 days
• Stimulation by antigen  large
plasma cell (producers of antibody)
•
Function:
Humoral immunity.
Lymphocytes
• B lymphocytes transform into plasma cells
and secrete antibodies
(17.6b)
Lymphocytes
• T lymphocytes can attack foreign cells
directly
(17.6)
T-Lymphocytes
(thymus dependent)
Formed in:
– bone marrow or lymphoid tissues
– migrate to thymus
Life span: 100-130 days.
Circulate between blood, tissues,
lymph.
T-Lymphocytes
(thymus dependent)
Types of T-lymphocytes
– T-helper
– T-cytotoxic
– Natural killer
Functions
– Cellular immunity
• graft rejection
• delayed hypersensitivity.
– Help in antibody secretion.
Helper T Cells
• Identified by
CD4
coreceptor.
• Indirectly
participate by
regulating the
response of
both T killer
and B cells.
• B cells must be
activated by
helper T cells
before they
produce
antibodies.
T Cell Response to a Virus
• Foreign antigens
attach to
immunoglobulins on
B cells.
• B cells can present
the antigen with
class-2 MHC
molecules to helper
T cells.
– Stimulate B cell
production,
conversion to
plasma cells, and
antibody production.
(continued)
Antibodies
(Immunoglobulins-Ig)
Antibodies
-(Immunoglobulins-Ig)
• Antibody is a gamma globulin produced
by plasma cells (B-lymphocytes)
• Subdivided into 5 classes:
–
–
–
–
–
IgG,
IgM
IgD
IgE
IgA.
• Bind specifically to the antigen
against which they have been
produced
Antibody
Humoral immunity
(Acquired immunity)
B-lymphocytes surface receptors
interact with antigen
B-lymphocytes proliferate to plasma
cells
Plasma cells secrete specific antibody
to destroy the antigen
• Some of the stimulated cells do not
proliferate stay dormant as
memory cells
Humoral immunity
(Acquired immunity)
• Action of Antibody
– Agglutination
– Precipitation
– Neutralization
– Lysis
Antibody –Antigen complex
Immune Response
in humoral immunity
The immune response of the body when
exposed to antigen
1. Primary immune response:
–
–
–
first exposure to antigen
antibodies formed after a latent period
one week (time needed for multiplication
and maturation of lymphocytes)
e.g. vaccination
Immune Response
in humoral immunity
2. Secondary immune response:
– second exposure to the same
antigen.
– immediate production of high titer
antibodies
– Memory lymphocytes (from first
exposure) act immediately when
exposed to the same antigen
Immune response
Cellular Immunity
Cellular immunity
• T-cell react with antigen by its
receptors and proliferate to give either:
– Cytotoxic (killer) T cells CD8 (Tc)
– Helper T cell CD4 (Th)
– Suppressor T cells (Ts)
T helper Cell
• Most numerous cells
• Major regulator of immune system
• Secret lymphokinese acts on other
cells of immune cells
– Stimulate growth of other T-lymphocytes
– Stimulate B-lymphocytes growth and
maturation into plasma cells
– Activation of macrophage system
Cytotoxic T cells
• T cell directly attack organism,
foreign infected cells and destroyed it
• Bind to antigen by surface receptors
making holes in it membrane
• Function:
– Rejection of transplanted tissues (kidney)
– Antitumor immunity
– Cooperation with B cell in humoral immunity
Cytotoxic T cells
Clinical application
• The Acquired Immune Deficiency
Syndrome (AIDS)
– Normal Th : Tc ratio = 2:1
– AIDS virus selectively attack Th
(CD4), ratio =1:2
– Generalize inhibition of immune
response
– Patient prone to bacteria/ viruses
infection & Cancer
Humoral immunity
Allergy
• Excess Antibody production:
hypersensitivity (allergy)
• Allergins: dust, pollen, drugs.
Leucocytosis
(Increased WBC Count)
Causes:
• Physiological
– Diurnal:  morning  evening
– After physical exercise
– Stress or Adrenaline injection
• Disease (pathological)
– Bacterial infections (tonsillitis,
appendicitis
– Worms infestations
Leucopenia
(Decreased WBC Count)
Causes:
– Malnutrition
– Typhoid fever
– Depressed bone marrow
– Deficiency of Vit B12 or folic acid
Leukaemia
(Cancer of white cells)
Causes:
• chromosomal abnormality
• chemicals, radiation, and viruses
WBC: > 50x103
Types of leukaemia
– Myeloblast leukaemia  myeloid cells
– Lymphoblast leukaemia  lymphocytic cells
• Acute or chronic
• Accompanied with anaemia, bleeding
Functions of Leucocytes- WBC
• Defence of the body against infections
and foreign invadors
Neutrophils & monocytes (Blood macrophages)- Phgaocytosist/
+ Immunity
Macrophage (RES) system …
Phagocytosis +
Immunity
Lymphcytes ….. IMMUNITY
‫‪THANK YOU‬‬
‫لكم جزيل الشكر‬