Main defense systems of body
Glands and their secretions
White blood cells : Lymphocytes
Originate in Bone marrow
Pluripotent hematopoetic stem cells
common lymphoid progenitor cells
Proliferation and education in THYMUS
Reaction against self-antigens ;90-95% cells
CD 4-helper T Cells
CD 8-cytotoxic T cells
Suppressor T Cells
Helper T cells; CD4
3/4 of T cells.
Types : TH1 and TH2
Major regulators : LYMPHOKINES PRODUCTION
(That act on other cells as well as on bone
Interlukin-2,3,4,5,6 , granulocyte-
monocyte colony stimulating factor,
AIDS; destruction of helper T cells
Stimulation of cytotoxic and suppressor T
Stimulation of B-cell growth and
differentiation to form plasma cell clones
Activation of Macrophage system
Feedback stimulatory effect on helper T cells
Killer cells ; CD8
Direct attack on micro-organisms
PERFORINS : hole-forming proteins
Release of cytotoxic substances into the
Cell swell and thus destroy.
Lethal to TISSUE CELLS invaded by VIRUSES.
Important role in destroying CANCER CELLS,
HEART TRANSPLANT CELLS, or other cells
foreign to body.
Less known cells
Suppress function of cytotoxic and helper T
Prevent damage to body itself
REGULATORY CELLS along with helper cells
These are activated by antigens but do not
enter in circulation
Remain in lymphoid organs
Migrate to various lymphoid tissues
throughout the body
If attacked by same antigen again,
More POWERFUL response
IMMUNE TOLERANCE; unresponsiveness of
immune system to any substance capable to
elicit immune response.
Developed in THYMUS ( self-antigen reaction)
BUT IF IT FAILS…….
AUTO-IMMUNITY: 2 types
Organ specific Organ non-specific
BYSANDER EFFECT; inflammation sensitizes
neighboring T cells which would not respond
“Defective immune system” pathogens
OPPURTUNISTS; organisms taking advantage
of defective defense mechanism.
CONGENITAL immunodeficiency diseases
(inherited defect in immune system)
ACQUIRED immunodeficiency diseases
( infection by some pathogen)
DIGEORGE’S SYNDOME; absence of thymus
SCID-Bubble boy disease; lack of ADA
enzyme due to defect at chromosome 22,
lymphoid tissue absent
Lymphoma: “solid tumor of
may develop in bone marrow , spleen,
lymph nodes, blood or any other organ.
Fast and abnormal division of lymphocytes .
Cd4 COUNT ; Less than 200 cells/mm3
while normal is 500-1500cells/mm3.
MODE OF ACTION:
Glycoprotein from HIV binds to specific
receptor on cd4 cells.
release of HIV RNA into host cell
action of REVERSE TRANSCRIPTASE
viral RNA viral DNA
new HIV form, host cell burst and virus
enter in bloodstream, infecting more cells,
INCUBATION PERIOD: No symptoms for several
weeks after exposure
Symptoms develop when sufficient number of
COMMON symptoms are ;
fatigue chronic diarrhea
loss of appetite night sweat
low-grade fever oral ulcers
vaginal ulcers etc
Which mostly kill the AIDS patient are
Kaposi sarcoma ( malignant skin cancer)
Respiratory tract infections
Mode OF TRANSMISSION:
Exposure to secretions from infected person i.e
through blood transfusion,from mother to fetus
and by vaginal sexual intercourse
Awareness among people
15OO-4000cells/ul of blood.
20;40% of total WBCs
LYMPHOCYTOSIS: “Increased lymphocytes”
1) ABSOLUTE L.C increased i.e. total
lymphocytes greater than 4000.
2 )RELATIVE L.C increased i.e. increased
proportion of lymphocytes than 40% but
Absolute count IS NORMAL
LYMPHOCYTOPENIA: “ Decreased
lymphocytes than 1000cells/ul.”
Is caused by activated T cells.
An inflammatory reaction
Secondary response appearing after 48-72
hours of exposure.
Poison ivy rash: serious tissue damage of skin
on repeated exposures.
T cells cause tissue rejection of any foreign
tissue or organ transplanted.
=> by killing T cells by Azathioprine.
=> inhibit cytotoxic T cells proliferation by
Glucocorticoids ( Cushing syndrome ).
=> immunosuppressive drugs such as