cells of immune system

1. PRESENTED
BY
TANIYA.M.S
MSC . BIOTECHNOLOGY

2. Cells of the Immune System-I
1. Originated from
Bone Marrow (BM)
2. Two major lineages:
- Lymphoid
- Myeloid
3. NK cells
- Large Granular
Lymphocytes (LGL)

3. Cells of Adaptive immunity
1. Lymphocytes are the key players of the adaptive
immunity.
2. Lymphocytes are able to specifically recognize and
respond to diverse antigens.
=> Antigen receptors on lymphocytes
=> Specificity Diversity & Memory
3. Lymphocytes are classified into three major groups:
- B cells => Antibodies => Humoral immunity
- T cells => Multiple subtypes => Cell-mediated immunity &
Regulate other immune cells
- NK cells => Innate immunity

4. Lymphocytes
 Specific receptores (TCR and BCR)
 Based on site of differentiation and on receptors:
T cells and naturall killers T - in thymus - (TCR)
B cells – bone marrow - (BCR)
(no cell surface specific receptors – NK cells)

5. Classes of Lymphocytes
1. B cells => Plasma cells
=> Abs
2. T cells:
- T helper cells
- T cytotoxic cells
- T regulatory cells
-T memory cells
-T NK cells
=> suppress immune
responses
3. NK cells
4. Subtypes in each class

6. Thymus derived cells
T lymphocytes
 Most important players of specific immunity
 Direct effectors and regulators of activity of other cells
Produced in bone marrow: not mature T cell – prothymocyte
Migrates in thymus - thymocyte, where TCR are produce.
 T cells and leave thymus and enter to ciruculation
Contain surface receptors TCR
 CD3, CD4 or CD8

7. - CD4 T cell
 2/3 of all T cells containging CD3
 CD4 cell surface molecule
– recognise part of MHC II
molecule that is not part
of peptid binding site
 Functionally – helper

9. - CD8 T cells
 1/3 of all T cells containing CD3
 CD8 cell surface molecule
– recognise part of MHC I
molecule that is not designated
to bind peptids
 Functionally :
Tc cytotoxic – eliminate virus
or i.c.bacteria infected cells
Ts supressor – increase and
control reactions of specific
immunity

11. Cells produced in bone marrow only
B - lymphocytes
 Not all cells produced in bone marrow migrate to
thymus
 Some differentiate in bone marrow further and are
precursors of cells producing immunoglobulins
 B lymphocytes – B cells – synthetise
immunoglobulin, that is then situated on the cell
surface as BCR.
 Differenciated mature B cell synthetises and
secretes immunoglobulines

14. B cells
 Plasma cells
 Memory cells
 B1 cells
 Regulatory cells

15. - Plasmatic cells
 Derived from terminally differentiated B cells
 Produce and secrete immunoglobulines
 In the momente, when they start to produce and
secrete Ig, they stop to use immunoglobuline
molecule as BCR
 They are bigger and have bigger metabolic activity
 Produce large amounts of Ig
 survive 30 days

16. NK cells – natural killers
 5% - 10% periferal blood lymphocytes
 do not have markers (receptors) as T cells
(CD3, TCR) and B cells (Ig)
 kill cells infected by viruses and tumor cells
without previous sensibilisation

17. Null cells
 A null cell is a large granular lymphocyte
 Without surface markers or membrane-associated
proteins from B lymphocytes or
T lymphocytes.
 Natural killer cells are usually null cells with
surface marker CD 16
 Attack pathogens and abnormal cells.
 Members of null cells are NK cells.
 In 75% of the cases of ALL, the
lymphocytes are neither B nor T-cells and
are called Null cells.

19. Classes of innate
immune cells
Innate immune cells are
classified as following:
- Monocyte/Macrophage
- Dendritic cell (DC)
- Polymorphonuclear
granulocyte (PMN;
Neutrophil, Eosinophil,
Basophil)
- Mast cell

20. WBC’s
 Five Types
 Classified according to the presence or absence of
granules and the staining characteristics of their
cytoplasm.
 Leukocytes appear brightly colored in stained
preparations, they have a nuclei and are generally
larger in size than RBC’s.

22. Type of WBC’s
 Granulocytes—have large granules in their
cytoplasm
 Neutrophils
 Eosinophils
 Basophils

23. Polymorphonuclear Granulocytes: Neutrophils
1. Comprise over 95% of
granulocytes
2. Short-lived (2-3 days)
3. Multi-lobed nucleus
4. Kill pathogens by
phagocytosis & releasing
cytotoxic substances.

25. Granuloctyes
 Neutrophils
 Stain light purple with neutral dyes
 Granules are small and numerous—course appearance
 Several lobes in nucleus
 65% of WBC count
 Highly mobile/very active
 Diapedesis—Can leave blood vessels and enter tissue space
 Phagocytosis (eater), contain several lysosomes (janitor)

26.  Neutrophils are a type of phagocyte.
 During the beginning phase of inflammation,
the first-responders of inflammatory cells to
migrate towards the site of inflammation.
 They migrate through the blood vessels,
then through interstitial tissue,
following chemical signals such as
Interleukin-8 (IL-8), Leukotriene B4 in a
process called chemotaxis.
 They are the predominant cells in pus,
accounting for its whitish/yellowish
appearance

28. Granulocytes
 Eosinophils
 Large, numerous granules
 Nuclei with two lobes
 2-5% of WBC count
 Found in lining of respiratory and digestive tracts
 Important functions involve protections against
infections caused by parasitic worms and
involvement in allergic reactions
 Secrete anti-inflammatory substances in allergic
reactions

29.  Eosinophils play a crucial part in the killing of
parasites (e.g., enteric nematodes) because their
granules contain a unique, toxic basic protein and
cationic protein

31. Granulocytes
 Basophils
 Least numerous--.5-1%
 Diapedesis—Can leave blood vessels and
enter tissue space
 Contain histamine—inflammatory chemical

32.  Basophils are one of the least abundant
cells in bone marrow and blood(occurring
at less than two percent of all cells).
 Like neutrophils and eosinophils, they have
lobed nuclei; however, they have only two
lobes, and the chromatin filaments that
connect them are not very visible.

34. Agranulocytes,
 mononuclear leukocytes,
 with a one-lobed nucleus.
 They are characterised by the absence of
granules
 2 types of agranulocytes in the blood
circulation are lymphocytes and monocytes.
 A third type of agranulocyte, the
macrophage is formed monocytes leave the
circulation and differentiate into
macrophages.

35. Agranulocytes
 Lymphocytes
 Smallest WBC
 Large nuclei/small amount of cytoplasm
 Account for 25% of WBC count
 Two types—T lymphocytes—attack an infect
or cancerous cell, B lymphocytes—produce
antibodies against specific antigens (foreign
body)

37. Agranulocytes
 Monocytes
 Largest of WBCs
 Dark kidney bean shaped nuclei
 Highly phagocytic

39. ROLES
 Replenishing resident macrophages under
normal states,
 In response to inflammation signals,
monocytes can move to sites of infection in
the tissues and divide/differentiate into
macrophages and dendritic cells to elicit an
immune response.
 Half of them are stored in the spleen
 Monocytes are usually identified in stained
smears by their large kidney shaped or
notched nucleus.
 These change into macrophages after
entering into the tissue spaces.

41. Macrophages
 Big eaters “( MΦ)
 That engulf and digest cellular debris, foreign
substances, microbes and cancer cells in a
process called phagocytosis .
 Beyond increasing inflammation and stimulating
the immune system,
 macrophages also play an important anti-inflammatory
role and can decrease immune
reactions through the release of cytokines.
 Macrophages that encourage inflammation are
called M1 macrophages, whereas those that
decrease inflammation and encourage tissue
repair are called M2 macrophages

42. Phagocytosis

44. Dendritic cells (DCs)
Accessory cells
 Dendritic cells were first described by Paul
Langerhans in the late 19th century.
 Antigen-presenting cells of the mammalian
immune system.
 Main function -process antigenmaterial
and present it on the cell surface to the t cells.
 Act as messengers between the innate and
the adaptive immune systems .

45.  Dendritic cells are present in those tissues that
are in contact with the external environment,
Eg. skin and the inner lining of
the nose, lungs, stomachand intestines.
also be found in an immature state in the blood.
 Once activated, they migrate to the lymph nodes
where they interact with T cells and B cells to
initiate and shape the adaptive immune
response.
 At certain development stages they grow
branched projections, the dendrite that give the
cell its name .
 Immature dendritic cells are also called veiled
cells, as they possess large cytoplasmic 'veils'
rather than dendrites

47. REFERENCE
 Campbell, Neil A., Reece Jane B., Biology
(6th edition), Pearson Education, Inc., 2002
 Delves, P.J., Martin, S. J., Burton, D. R.
and Roit I.M. Roitt's Essential Immunology
(11th edition), Blackwell Publishing, 2006,
 Ernst J. D. and Stendahl O., (editors),
Phagocytosis of Bacteria and Bacterial
Pathogenicity, Cambridge University Press,
2006,
 Hoffbrand, A.V., Pettit, J.E. and Moss,
P.A.H., Essential Haematology (4th
edition), Blackwell Science, 2005

48. Thank you