Functions of T Lymphocytes
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Transcript of Functions of T Lymphocytes
FUNCTIONS OF
T LYMPHOCYTES
BY:
Roll
NO:102,108,114,120
,126
Presented by:1. Memoona Zamurad (102)2. Maryam Ikram (108)3. Mavra Hafeez (114)4. Mommal Rasool (120)5. Noreen Riaz (126)
INTRODUCTION
Main defense systems of body Skin Glands and their secretions White blood cells : Lymphocytes
B Lymphocyt
es
T Lymphocyt
es
Anti body production
Self activation
ORIGIN AND PROCESSING:
Originate in Bone marrow Pluripotent hematopoetic stem cells
common lymphoid progenitor cells Proliferation and education in THYMUS
gland. Reaction against self-antigens ;90-95%
cells destroyed. Specificity
TYPES OF T LYMPHOCYTES CD 4-helper T Cells CD 8-cytotoxic T cells Suppressor T Cells Memory cells
HELPER 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
marrow) Include;
Interlukin-2,3,4,5,6 , granulocyte-monocyte colony stimulating factor, interferon-&.
AIDS; destruction of helper T cells
FUNCTIONS OF HELPER CELLS; Stimulation of cytotoxic and suppressor
T cells. Stimulation of B-cell growth and
differentiation to form plasma cell clones
Activation of Macrophage system Feedback stimulatory effect on helper T
cells themselves.
DIAGRAM
CYTOTOXIC T CELLS Killer cells ; CD8 Direct attack on micro-organisms PERFORINS : hole-forming proteins Release of cytotoxic substances into the
attacked cells 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.
SUPPRESSOR T CELLS Less known cells Suppress function of cytotoxic and
helper T cells. Prevent damage to body itself REGULATORY CELLS along with helper
cells IMMUNE TOLERANCE:
MEMORY T 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,
immediate response. More POWERFUL response
DISORDERS RELATED TO T LYMPHOCYTES
Autoimmune disorders
Immune deficiency diseasesAllergic reaction
Tissue rejection
AUTO-IMMUNITY 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 normally
IMMUNO DEFICIENCY DISEASES “Defective immune system” pathogens
attack easily OPPURTUNISTS; organisms taking
advantage of defective defense mechanism.
2 TYPES: CONGENITAL immunodeficiency
diseases (inherited defect in immune system)
ACQUIRED immunodeficiency diseases ( infection by some pathogen)
T CELLS RELATED CONGENITAL DISORDERS: DIGEORGE’S SYNDOME; absence of
thymus gland genetically SCID-Bubble boy disease; lack of ADA
enzyme due to defect at chromosome 22, lymphoid tissue absent
ACQUIRED DISEASES OF T-CELLS AIDS LYMPHOMA Lymphoma: “solid tumor of
lymphoid cells” may develop in bone marrow , spleen,
lymph nodes, blood or any other organ. Fast and abnormal division of
lymphocytes .
AIDS ( ACQUIRED IMMUNE DEFICIENCY SYNDROME) Cause; HIV 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,
SYMPTOMS OF AIDS INCUBATION PERIOD: No symptoms for
several weeks after exposure Symptoms develop when sufficient number
of cells ruptured COMMON symptoms are ; fatigue chronic diarrhea loss of appetite night sweat low-grade fever oral ulcers vaginal ulcers etc
OPPURTUNISTIC INFECTIONS: Which mostly kill the AIDS patient are Pneumocystis pneumonia Kaposi sarcoma ( malignant skin cancer) Respiratory tract infections Lymphomas Mode OF TRANSMISSION: Exposure to secretions from infected person
i.e through blood transfusion,from mother to fetus and by vaginal sexual intercourse
PREVENTION; Awareness among people Blood screening
NORMAL LYMPHOCYTE COUNT AND ABNORMALITIES 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.”
ALLERGY-DELAYED RESPONSE 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. Lungs edema Aesthematic attacks
TRANSPLANT REJECTION T cells cause tissue rejection of any
foreign tissue or organ transplanted. PREVENTION => by killing T cells by Azathioprine. => inhibit cytotoxic T cells proliferation
by Glucocorticoids ( Cushing syndrome ).
=> immunosuppressive drugs such as Cyclosporine.