Macrophage Phagocytosis Question and Answers

Host Response – Basic Concepts Important Notes

1. Leucocytes

• Leucocytes constitute a major protective mechanism against the extension of plaque into the sulcus
• Leucocytes are attracted by plaque bacteria

2. Leukotoxin

• Leukotoxin is an exotoxin produced by A.a. contains which has a toxic effect on PMNs
• Leukotoxin enables these microorganisms to evade the host defense of phagocytosis

Read And Learn More: Periodontics Question and Answers

3. Interleukin-1-includes

• Osteoclast activating factor – causes bone resorption
• Lymphocyte activating factor – has the ability to stimulate the proliferation of T cells
• Interleukin-1 and TNF are key cytokines in the pathogenesis of periodontitis

4. Prostaglandin Ez

• The cells that produce it in periodontium are macrophages and fibroblasts
• It induces the secretion of metal matrix proteins and osteoclastic bone resorption
• Contributes to the loss of alveolar bone as seen in periodontitis

Host Response – Basic Concepts Short Essays

Question 1. Role of saliva in oral defense mechanism.
Answer:

• Swallows bacteria
• Inhibits bacterial attachment
• Bacteriocidal action

Peroxidase System:

Peroxidase (Synthesize by ductal cells)
↓
Bound to bacteria (or) Hydrogen peroxide (secreted by bacteria, neutrophils & host cells)
↓
This combines with thiocyanate secreted by ductal cells
↓Oxidation

This leads to hypothiocyanous acid
↓
Causes the death of bacteria

Lactoferrin:

Secreted by serous salivary gland
↓
Binds to iron
↓
Cut off nutrition to bacteria
↓
Results in bacteriostatic action

Lysozyme:

Secreted by mucous salivary gland
↓
Degrades cell wall
↓
Lysis of cell

Question 2. Phagocytosis.
Answer:

Phagocytes reach the site of inflammation
↓
Opsonization recognizes micro-organisms coated by Cзb
↓
Attach to them
↓
Extends pseudopodia and engulfs microorganisms
↓
Fusion of lysozymes and phagosomes occurs
↓
Resulting in phagolysosome
↓
Kill the infectious agent by following the mechanism

1. Oxidative:

• Stimulation of Phagocytes
• This leads to increased O₂ consumption
• Formation of O₂ metabolite
• Conversion of the phagocyte to superoxide anion
• Conversation to H₂O₂ [microbicidal]

2. Non-Oxidative:

• Granules involved
  • Primary granules
  • Secondary granules
  • Tertiary granules

Question 3. Lymphocytes.
Answer:

Lymphocytes Types:

1. T-cells:

• Derived from thymus
• Secrete prostaglandins

Helper T-cell (TH):

• CD₄
• Releases IL₂ and Interferon
• In adult periodontitis, TH increased

Suppressor T-cell (TS):

• CDa
• Releases IL₄ and IL₅

2. B-Cells:

• Derived from the liver, spleen, and bone marrow
• Help in humoral immunity

3. Natural Killer Cells:

1. Plaque antigens diffuse through the junctional epithelium
2. Langerhans cells within the epithelium capture and process the antigens
3. Antigen-presenting cells (macrophages & Langerhans cells) leave the gingiva in the lymphatics
4. Antigen-presenting cells reach the lymph node and begin to stimulate lymphocytes to produce a specific immune response
5. Periodontal microbe-specific antibodies are produced by plasma cells within the lymph nodes and travel back to the gingiva via blood vessels
6. Antibodies leave the circulation and are carried to the crevice in the transudate from the inflamed and dilated blood vessels
7. Antibody action on microbes in the crevice can result in killing, aggregation, precipitation, detoxification, opsonization, and phagocytosis of bacteria

Lymphocytes Functions:

Recognizes antigen:

Divides and provides a large no. of cells called “clonal expansion”
↓
Differentiate into
↓
Humoral responses
Different lymphocytes into plasma cells Secret es antibody

Question 4. Inflammatory cells.
Answer:

1. Neutrophils:

• The first cell of defense
• Exit circulation and reach the site

Neutrophils Functions:

• Emigration:
  • Neutrophils adhere to endothelial cells
  • These, then migrate across the endothelium
• Chemotaxis:
  • Attracted by chemical signals from multiple sources
• Phagocytosis:
  • Attaches to micro-organisms and engulfs it

2. Macrophages:

• Develop from blood monocytes
• Migrate to the site of inflammation
• Triggered by cytokines, inflammatory mediators, and bacterial products

Macrophages Functions:

• Phagocytose kill bacteria
• Remove damaged host tissue
• Present antigens to lymphocytes
• Secretes inflammatory mediators
• Secretes tissue-damaging enzymes
• Secretes complement components

Host Response – Basic Concepts Short Answers

Question 1. Complement.
Answer:

Complement Components: C1-C9

Complement Effect: Cytolytic and cytotoxic damage to cell

Question 2. Neutrophils.
Answer:

• The first cell of defense
• Exit circulation and reach the site

Neutrophils Functions:

1. Emigration:

• Neutrophils adhere to endothelial cells
• These, then migrate across the endothelium

2. Chemotaxis:

• Attracted by chemical signals from multiple

3. Phagocytosis:

• Attaches to micro-organisms and engulfs it

Question 3. Antibacterial factors in saliva.
Answer:

• The antibacterial action of saliva is through

1. Perioxidase System:

Peroxidase (Synthesize by ductal cells)
↓
Bound to bacteria (or) Hydrogen peroxide (secreted by bacteria, neutrophils & host cells)
↓
This combines with thiocyanate created by ductal cell
↓
Oxidation
This leads to hypothiocyanous acid
↓
This leads to hypo thiocyanic acid
↓
Causes the death of bacteria

2. Lactoferrin:

Secreted by serous salivary gland
↓
Binds to iron
↓
Cut off nutrition to bacteria
↓
Results in bacteriostatic action

3. Lysozyme:

Secreted by mucous salivary gland
↓
Degrades cell wall
↓
Lysis of cell

Question 4. Any 5 Neutrophil disorders causing periodontitis.
Answer:

• Papillon Lefevre syndrome
• Down’s syndrome
• Chediak-Higashi syndrome
• Agranulocytosis
• Cyclic Neutropenia

Question 5. Functions of leukocytes
Answer:

1. Phagocytosis:

• Leukocytes engulf bacteria and foreign material

2. Chemotaxis:

• Enables leukocytes to locate their target

3. Antiallergic effect:

• Eosinophil inhibits histamine release during allergic conditions

4. Antibody formation:

• Lymphocytes are responsible for antibody formation

5. Heparin production:

• Basophils produce heparin which prevents in-intravascular clotting

6. Trephone formation:

• Leukocytes help in the formation of the telephone from plasma proteins

Question 6. Functions of IgG.
Answer:

Functions of IgG:

• Complement fixation Delayed antibody response
• Opsonization
• Cross placental barrier
• Increased concentration in GCF

Question 7. Name functional defects of leukocytes.
Answer:

Host Response – Basic Concepts Viva Voce

1. Predominant immunoglobulin in saliva is IgA
2. Orogranulocytes are PMNs that reach the oral cavity