Guide
With Questions and Answers – Graded A+
Tissue-Resident Sentinel Cells
There are three main types of tissue-resident sentinel cells: dendritic cells,
macrophages, and mast cells. These cells play a crucial role in the immune response
by detecting and responding to potential threats.
Circulating Leukocytes in the Innate Response
The two primary types of circulating leukocytes involved in the innate immune
response are monocytes and neutrophils. These cells help the body fight infections
by identifying and attacking foreign invaders.
Phagocytic Immune Cells
Two key immune cells that specialize in phagocytosis (engulfing and digesting
harmful particles) are macrophages and neutrophils.
Macrophages vs. Neutrophils – What’s the Difference?
• Neutrophils have a short lifespan and undergo apoptosis (programmed cell death) after
consuming a microbe.
• Macrophages, on the other hand, live longer and are capable of engulfing apoptotic cells
and clearing cellular waste.
Cytokines and Their Role in the Innate Immune Response
Cytokines are pro-inflammatory molecules released by dendritic cells,
macrophages, and mast cells. Their function is to interact with blood vessel
endothelium, helping to recruit circulating leukocytes, fluid, and proteins into the
affected tissue.
Which Tissue-Resident Sentinel Cell Releases Histamine?
The mast cell is responsible for releasing histamine when activated, playing a vital
role in inflammation and allergic reactions.
, Cytokines and Adhesion Molecules
Cytokines promote the upregulation of adhesion molecules within blood vessel
walls. These molecules assist in guiding immune cells to the site of infection or
injury.
Key Adhesion Molecules in the Immune Response
• E-Selectin: This adhesion molecule slows down circulating leukocytes during the innate
immune response by forming low-affinity interactions.
• E-Selectin Ligand: A ligand expressed by circulating leukocytes, helping them stick to blood
vessel endothelium.
• ICAM-1: Another adhesion molecule, but with high-affinity interactions, aiding in the
binding of leukocytes to blood vessel walls.
• Integrins (e.g., LFA-1): These molecules are present on circulating leukocytes and allow
strong adhesion to ICAM-1 during inflammation.
Stable Arrest – What Is It?
This occurs when a circulating leukocyte completely stops within the endothelium
due to adhesion molecule interactions, allowing it to enter the surrounding tissue.
What Is Pus?
Pus is a byproduct of inflammation, consisting of fluid, apoptotic cells, DNA, dead
bacteria, and neutrophils that have undergone programmed cell death.
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Psoriasis Overview & Immune System
Concepts
Psoriasis – What Is It?
Psoriasis is an autoimmune condition that can lead to skin plaques and arthritis.
The skin plaques develop because immune cells migrate into the skin, triggering an
inflammatory response.
Risk Factors for Psoriasis
Several factors can increase the likelihood of developing psoriasis, including: