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Functions of T Lymphocytes


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A presentation about the various Functions of T Lymphocytes, and the Clinical problems that arise when their balance is disturbed.

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Functions of T Lymphocytes

  1. 1. Presented by: 1. Memoona Zamurad (102) 2. Maryam Ikram (108) 3. Mavra Hafeez (114) 4. Mommal Rasool (120) 5. Noreen Riaz (126)
  2. 2.  Main defense systems of body  Skin  Glands and their secretions  White blood cells : Lymphocytes B Lymphocytes T Lymphocytes Anti body production Self activation
  3. 3.  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
  4. 4.  CD 4-helper T Cells  CD 8-cytotoxic T cells  Suppressor T Cells  Memory cells
  5. 5.  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
  6. 6.  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.
  7. 7.  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.
  8. 8.  Less known cells  Suppress function of cytotoxic and helper T cells.  Prevent damage to body itself  REGULATORY CELLS along with helper cells  IMMUNE TOLERANCE:
  9. 9.  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
  10. 10. Autoimmune disorders Immune deficiency diseases Allergic reaction Tissue rejection
  11. 11.  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
  12. 12.  “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)
  13. 13.  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
  14. 14.  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 .
  15. 15.  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,
  16. 16.  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
  17. 17. 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
  18. 18.  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.”
  19. 19.  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
  20. 20.  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.