1. Cells & Organs of the immune system Dr. Mohed. Shaker

2. Cells involved in immunity
platelets
eosinophil
megakaryocyte
T Lymphocyte
Pluripotent
hematopoietic
stem cell
neutrophil
B Lymphocyte
common lymphoid progenitor
basophil
common myeloid progenitor
Study Guide
Can you describe the major classes of cells involved in immunity?
Which cells are considered mononuclear leukocytes?
What is the relationship between the monocyte and the macrophage?
What is the relationship between the B-cell and the plasma cell?
plasma cell
mast cell
Natural
Killer cell
monocyte
macrophage

3. Polymorphonuclear leukocytes (or Granulocytes)
Where is that stuff?
Blood
Serum or Plasma
Leukocytes, Platelets and RBC
Mononuclear Cells
Polymorphonuclear leukocytes (or Granulocytes)
Serum Proteins
Immunoglobulins
Complement
Clotting factors
Many others
Lymphocytes (T cells, B cells & NK cells)
Monocytes
Neutrophils
Eosinophils
Basophils

4. Lymphoid Organs Primary or central lymphoid organs
bone marrow and thymus
where lymphocytes are generated
Secondary or peripheral lymphoid organs
where adaptive immune responses are initiated

5. Distribution of Lymphoid Tissues

6. Response to Initial Infection

7. Stages of Response to Infection

8. Course of Typical Acute Infection

9. Immune Cells and Innate Immunity
Phagocytes
Neutrophils
Moncyte/macrophage
Eosinophils (to a lesser extent)
NK cells (large granular lymphocytes)
Antibody-dependent cell-mediated cytotoxicity (ADCC)
Have two major functions
Lysis of target cells
Production of cytokines (IFN-g and TNF-a)
Act against intracellular pathogens
Herpesviruses
Leishmania
Listeria monocytogenes
Act against protozoa
Toxoplasma
Trypanasoma

10. Immune Cells and Innate Immunity (cont’d)
g/d T cells
Two types of T cell receptors
One composed of a and b chains (basic T cell antigen receptor)
One composed of g and d chains (minor population of T cells)
Two groups of g/d T cells
One group found in lymphoid tissues
One group located in paracellular space between epithelial cells
Recognizes unprocessed target antigen in absence of APC help
B-1 cells (minor fraction of B cells, do not require T-cell help)
Mast cells
Located in serosa, under epithelial surfaces and adjacent to blood vessels, nerves and glands
Capable of phagocytosis
Process and present antigen using MHC class I or II receptors
LPS can directly induce release of mast cell mediators
Complement (C3a and C5a) induce mast cells to release mediators
Chemotaxis, complement activation, inflammation
TNF-a secreted by mast cells results in neutrophil influx into infected site

11. Summary of Innate Immunity
External and mechanical barriers
Receptors for pathogen motifs
Soluble antimicrobial proteins
Pattern of cytokines produced influences adaptive response