Question

Innate immunity: metaphor

Imagine the siege of a castle. All of a sudden, the besiegers break through the castle’s defenses. During the invasion, the invader breaches the castle’s first line of defense. The defenders meet it with more powerful weapons and specialized troops. The same scenario is true of invading pathogens. Think of another logical metaphor that explains the features and functioning of the innate immune system. Draw your metaphor in cartoon-style, label each of the following immune-system components in your drawing and add a legend that explains the metaphor in a few sentences. Include the following components of the innate (or non-specific) immune system:

• Pathogen
• Physical barrier
• Pathogen recognition
• Inflammatory response with neutrophils and macrophages

Answer 1

Actual event:

• Immune response is initiated when the body encounters any foreign molecules acting as exogenous or endogenous antigens) or a pathogen.
• The innate immunity or non-specific immunity acts as the first line of defense, provides barrier against the foreign substances.

Innate immunity, is in born immunity and act as first line of defense. Innate immunity is non-specific, and include:

1) Anatomical barriers or physical barrier include a) .skin- epidermis layer of skin has protective waterproofing keratin protein and dermis layer bear sebaceous glands which produce sebum, that inhibit growth of many microorganisms. B) mucous membrane- are washed and protected by mucous, tears or saliva. Also has ciliated epithelial cells that entraps microbes.

2) Physiological barriers include body temperature, pH (potential of hydrogen), soluble molecules like lysozymes, interferons.

3) Inflammatory response- complex sequence of events, resulting after pathogen invasion through a wound or damage. Results in four typical cardinal signs, rubor (redness), tumor (swelling), calor (heat) and dolor (pain).

4) Phagocytic response- phagocytosis is mediated by endocytosis process of phagocytic cells like macrophages and neutrophils.

• Various cytokines released from specific cells, like interleukins (IL), tumor necrosis factor alpha (TNFα), activates the production of mature phagocytic cells, like neutrophils, macrophages and dendritic cells and induce their migration to the site of infection or invasion.
• Phagocytic cells, engulf the foreign substances by phagocytosis or endocytosis.
• The phagocytosed molecules processed and, then the peptide fragments of antigens are expressed through membrane bound glycoproteins called major histocompatibility complex (MHC).
• This help in pathogen recognition and further activation of humoral (antibody mediated) or cell mediated immune responses.

Metaphor with legend:

• A kingdom has a border from the enemy of the land.
• The barbed wire fenses are similar to the anatomical barrier.
• At night some enemies cut the barbed wires. This is analogous to the attack by pathogens by breaking through the skin or mucus membrane.
• The wire border was however attached to a siren system, which sends a signal to the defense head. Similarly, the cytokines act as signal mechanism to signal to phagocytotic cells like macrophages and dendritic cells. The soldiers with their special weapons act as phagocytic cells that will require few minutes to load their weapons and defenses.
• However, there are other barriers that the enemy must cross, which will give time to the soldiers to get ready for their defense and attack.
• These barriers include a big ditch with acids followed by hot water.
• These are similar to physiological barrier.
• If the enemies enter passing through the barriers the soldiers then reach and establish a defense and attack.
• The enemies may mix with the common men of the area, thus, a recognition system has been established by the defense head.
• All the residents of the kingdom has a token of identity which proves they belong to the kingdom. The enimies may thus be recognized by the soldiers.
• The pathogen recognition is established by certain surface proteins as expressed by the MHC molecules.

(enemy (enemy identified Pathogens o Pathogen peen Matem Border (Anatomical - Barpiest (Physiological Ditch - Residents (self antigens) I Defense cells Soldiep (Soldiers (macrophages Blood vessels anadendritic defoncetton) caels.