ImmunologyDendritic cells (DCs)

Are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface

to other cells of these immune system. dendritic cells function as antigen-presenting cells. At certain development stages they grow branched projections, the dendrites

that give the cell its name. They act as messengers between the innate and adaptive immunity.

Dendritic cells are present in 1. tissues in contact with the external environment, such as the skin (Langerhans

cells) 2. The inner lining of the nose, lungs, stomach and intestines. 3. They can also be found in an immature state in the blood.

The role of dendtrics in periodontitis treatment is by developing a therapy that block signal 2 of the antigen presenting and keeping signal 1(danger signal) intact.

The complement system 

It is part of the immune system   It can be recruited and brought into action by the adaptive immune system. The complement system consists of a number of small proteins found in the

blood, generally synthesized by the liver, and normally circulating as inactive precursors (pro-proteins). When stimulated by one of several triggers,  it releases cytokines and initiate an amplifying cascade and the end-result of is massive amplification of the response and activation of the cell-killing membrane attack complex.

Bone marrow is the supplier for :1. Lymphoid stem cell that give rise to T cell B cell which give plasma cell then Ab CD4 and CD8 cell from thymus2. Myeloid stem cell that give rise to Macrophage Platelet RBC Neutrophil

Circulating immune cell. 1. Blood cells Leukocyte which includes:

A. mononuclear cells like lymphocyte (T cells, B cells, RBC, Platelets)

B. multinuclear like neutrophile, esonophil, basophil

Phagocyte like monocyte2. Tissue cells like mast cells, macrophages, tissue neutrophile, t cells, b cells

Macrophages1. Few Macrophages resident in healthy Periodontal tissue

2. Respond directly to pathogen in tissue

3. Respond indirectly to cytokines

4. Start to eat up and break down pathogen (phagocytosis)

5. Recruit neutrophils by releasing neutrophil attractants

Neutrophile 1. Infiltrate in large numbers

2. Recruit more macrophages

3. Highly motile reach site of inflammation quickly and act by Phagocytosis

4. Reactive Oxygen species

5. enzymes and antimicrobials

6. Cytokine/chemokine secretion

Adaptive immunity• Specificity in recognition of foreign substances/ antigens

• Occurs through functional receptors on B and T cells

– B-cell activation leads to plasma cells and secretion of immunoglobulin (humoral response)

– T-cell receptors recognise antigenic determinants/epitopes (cellular immunity) keeping in mind that T-cell activation requires help from Antigen Presenting Cells [APCs]

Cellular immunity (T lymphocyte)• T lymphocytes regulate immune responses and cell-mediated immunity

• Two major T cell classes:

• helper T cells ( CD4 cells) TH cells assist in activation of antigen-presenting cells to kill intracellular bacteria (TH1) or help B cells produce antibody (TH2)

through B cells, macrophages

• cytotoxic T cells (CD8 cells) kill target cells by inducing apoptosis

Humoral immunity• Acquired immunity regulated by antibody (immunoglobulin- IgG, IgA, IgM,

IgE, IgD)

• B lymphocyte recognition of foreign antigen by membrane-bound receptor (antibody)

• Initiates proliferation/ differentiation of B-cell into antibody-producing plasma cells

Features of innate immunity• Present from birth

• First line of defense

• Responses are generic manner

• No-memory

• pattern recognition receptors (PRRs) lead to triggering of signal pathways resulting in inflammation .

• Toll-Like Receptors (TLRs) recognize constituents of microb.

• Effective: it is effective with the pathogens that are destroyed within minutes or hours

Innate Immunity and its function

Physical/anatomical barriers

Cellular mechanismsPlasma factors

Antigen presentationPhagocytosisMediator release Complement

Tissues

Macrophages

Blood

Monocytes Macrophages

Osteoclastogenesis leads to bone loss (Resorption)• Mediated by Osteoclasts

• Activation of (RANK) receptor

Osteoblastogenesis leads to bone formation• Mediated by Osteoblasts

• Osteoblasts secrete Osteoprotogerin OPG

Mode of action of periostat (doxycyclin)1. Inhibit reactive O2 (ROS)2. Inhibit MMPs3. Decrease chemical mediators4. Enhance Scavengers5. Stimulate fibroblast6. Reduce osteoclast