Cells of the immune system in Human. www.BiochemDen.in

1. IMMUNOLOG
Y
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2. Cells of the
Immune system
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3. Stem cells
The cells which develop into the blood cells are
called Stem cells
They are Undifferentiated embryonic cells
They have the ability to develop into any type
of Red blood cells. So they are said to be Pluripotent
and Totipotent
The stem cells develop in three lines, namely
lymphoid lineage, Myeloid lineage and Erythroid lineage
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4. Stem cell
Myeloid
lineage
Lymphoid
lineage
Erythroid
lineage
Erythropoisis
RBC
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5. Lymphoid lineage
Lymphoid Progenitor
T-Lymphocytes B-Lymphocytes Null cells
Natural Killer cells Killer cells
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6. Myeloid lineage
Polymorpho
nuclear
leucocytes
Monocytes
1. Eosinophils
2. Basophils
3. Neutrophils
4. Mast cells
5. APC
6. Megakaryocytes Platelet
Macrophages (MΦs)
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7. Lymphocytes
Lymphocytes are mononucleate, nongranular leukocytes of lymphoid
Lymphocytes are the “Central cells of the immune system”,
responsible for acquired immunity & the immunological attributes of
diversity, Specificity, many and self / nonself recognition.
Lymphocytes constitute
20% to 40%  body’s WBC
90%  cells in the lymph
Lymphocytes are subdivided into THREE
populations
B-Cells, T-Cells, Null cells
tissue, participating in immunity.
They are found in blood, lymph, and lymphoid tissues such as Spleen,
lymph nodes, tonsils, payer's patches, appendix.etc.
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9. B-Lymphocytes
The letter “B” designated from its site of maturation:
Bursa of fabricus  in birds
Bone marrowin mammalian species
B-lymphocytes carries out “Humoral immune response” by producing antibodies.
Each of the cell contains approximately 1.5X105 molecules of antibody on the
membrane of a single B-cell has an identical binding site for antigen
B-lymphocytes are stimulated by TH-lymphocytes
When the antigen stimulate, the B-cell divides repeatedly & differentiate over a 4 to 5 day
period, generating a population of Plasma cell and Memory cell.
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10. T-lymphocytes
The letter “T” designates from its site of maturation in the
“Thymus”
T-Cells regulate the “Cell mediated immunity”
The T-cell receptors on their membrane surface (cell markers),
which belongs to an important group of molecules known as
“Major Histocompatibility Complex (MHC).
The T-lymphocytes can be divided into THREE types
1) T-helper cells
2) Cytotoxic T-cells
3) Suppressor T-cells
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11. TH- lymphocytes
1. The T-cells interact with MHC-II molecules, present on the surface of the
macrophage surface.
2. The cells produce variety of soluble factors known as “Cytokines”.
3. The cytokines increase the response of B-cells, T-killer cells and T-suppressor
cells.
4. The lymphocytes also secrete another lymphokine called “Macrophage
Migration inhibition factor”
Cytotoxic T-cells
1. The cells clonally express a large number of differentiate surface markers
2. These cells attack infected cells and cancer cells
3. The cells discharge a protein called “Perforin”, which lyses the infected
cell.
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12. Null cells
1. Null cells are the small group of lymphocytes in the peripheral blood do not
express the membrane in nucleus & receptors that distinguish T & B-cells.
2. Null cells fail to synthesize Immunoglobulin because these cells do not
produce “Antigen-binding receptors”.
There are TWO types of null cells namely,
1. Natural Killer Cells (NK cells)
2.Killer Cells (K cells)
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13. 1. Natural Killer Cells (NK cells)
• Natural killer cells form the third population
of lymphocytes.
• NK cells have a Kidney shaped nucleus.
• Cell surface possess FC receptors for Ig and
CR3 receptor for complement.
• They destroy the cancer cells and cells infected with herpes and
mumps virus.
• They do not need antibody for activity.
• They are activated by Interferon-1 and Interferon-2
• They recognize altered cell surface and bring about cytolysis and
cytotoxicity. www.BiochemDen.in

14. 2.Killer cells (K cells):
•They are antibody dependent cells.
•These cells possess Fc receptors for binding with
IgG antibodies.
•It is termed as “Antibody-Dependent Cell-mediated
Cytotoxic reaction (ADCC)”
•The cells kill a variety of cells such as tumor cells,
Bacteria, viruses, fungi and parasites.
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15. Myeloid lineage
Polymorpho
nuclear
leucocytes
Monocytes
1. Eosinophils
2. Basophils
3. Neutrophils
4. Mast cells
5. APC
6. Megakaryocytes Platelet
Macrophages (MΦs)
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16. Polymorpho Nuclear Leucocytes
1. Eosinophils:
1. Eosinophilic cells constitute about 2 to 5% of WBC.
2. These are acidophilic leukocytes and are called
eoisinophils.
3. Eosinophils has a bilobed nucleous & granulated
cytoplasm that stains with the acid dye “EOSIN” red.
4. It play a significant phagocytic role like Macrophages.
5. In allergic conditions the cell count will increase.
6. Granules present in the cells & it contains hydrolytic
enzymes.
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17. 2. Basophils
1. Basophils constitute about 0.4% of white blood cells.
2. The basophilic granules are believed to contain HEPARIN.
3. It has a lobed nucleus and heavily granulated cytoplsm that
stains with the basic dye “Methylene blue”
4. The cells release pharamalogically agents like Histamine,
Seratonine, platelet activating factor and vasoactive amines
at inflammation regions.
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18. 3. Neutrophils:
1. Neutrophils constitutes about 40 to 75% of WBC cells.
2. It has a multi-lobed nucleus & granulated cytoplasm that stains with
both acid & basic dyes.
3. It is often called a “Polymorphonuclar leukocytes (PMN)”.
4. The cells contains primary & secondary granules:
larger, denser granules  Peroxidase, Lysozyme,
& Various hydrolytic enzymes.
Smaller. Secondary granules Collagenase, Lactogenase & Lysozyme
4. The cells exhibit a larger “Respiratory Burst”
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19. 4. Mast cells:
1. Mast cells are about 10 to 30mm in diameter and they have
polymorphous nucleus.
2. The cells are similar to basophilis of the blood, in appearance and
function.
3. It play an important role in the development
4. The mast cells are of two types
Mucosal Mast cells
 found in the mucosa of the lung and GUT.
The cells are dependant on lymphocytes
for differentiation.
Connective tissue Mast cells
 Present at the sites of immediate
hypersensitivity reactions.
The granules of mast cells release substances
Seratonine, Histamine, Heparin, Leukotrienes, Prostaglandins and Platelet activating factor
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20. 5. Antigen Presenting Cells:
The immune system contains of three types of antigen presenting cells
(APC's).
1.Macrophages
2. B-cells
3.Dendritic cells
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21. Monocytes
Macrophages (MΦs)
1. Macrophages are phagocytic cells, derived from the blood
Monocytes.
2. Macrophages are the part of the INNATE IMMUNITY.
3. The macrophages are amoeboid cells having bilobed nucleus
& predominant cytoplasmic lysosomes.
4. Macrophages like cells serve different functions in different
tissues & are named according to their tissue location.
Alveolar Macrophages  In Lungs
Histocytes  In connective tissues
Kupffer cells  In the Liver
Mesangial cells  In the Kidney
Microglial cells  In the Brain
Osteoclasts  In the Bone
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22. THANK
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