N. Inflammatory Cells & Mediators 

Main Types of Inflammatory Cells

• Neutrophils: The first responders in acute inflammation. They quickly move to sites of bacterial infection or injury and engulf microbes.

• Lymphocytes: Include T cells (which kill infected cells and regulate immune responses) and B cells (which produce antibodies). They are more prominent in viral infections and chronic inflammation.

• Plasma Cells: Derived from B cells, they specialize in producing large amounts of antibodies to fight infection.

• Macrophages: Long-lived cells that engulf pathogens and debris, release signaling molecules, and help with tissue repair. They dominate in chronic inflammation.

• Eosinophils: Important in allergic reactions and defense against parasites. They release toxic proteins that can damage invaders but also contribute to tissue injury in conditions like asthma.

• Basophils and Mast Cells: Release histamine and other chemicals that trigger allergic responses and contribute to inflammation.

How They Work

• Recruitment: Chemical signals (cytokines, chemokines) attract these cells to the site of injury or infection.

• Defense: They attack pathogens directly (through phagocytosis or cytotoxic activity) or indirectly (by producing antibodies and signaling other cells).

• Cleanup: Dead cells and debris are removed, mainly by neutrophils and macrophages.

• Repair: Growth factors released by these cells stimulate tissue regeneration.

Clinical Importance

• Acute inflammation (like bacterial infections) → neutrophils dominate.

• Chronic inflammation (like tuberculosis or autoimmune diseases) → macrophages and lymphocytes are more common.

• Allergic conditions (like asthma or eczema) → eosinophils and mast cells play a major role.

Would you like me to also explain the difference between acute and chronic inflammation in terms of how these cells behave? That’s often the clearest way to see their roles in action.

Inflammatory Mediators: An Overview

Inflammatory mediators are chemical messengers that orchestrate the body’s defense response to infection, injury, or irritation. They are released by immune cells, endothelial cells, and damaged tissues to initiate and regulate inflammation. Their role is to recruit immune cells, increase blood flow, and trigger healing processes.

Major Categories of Inflammatory Mediators

Category

Examples

Key Functions

Vasoactive amines

Histamine, Serotonin

Cause vasodilation, increase vascular permeability, promote swelling and redness

Lipid-derived mediators

Prostaglandins, Leukotrienes

Regulate pain, fever, vascular changes, and leukocyte recruitment

Cytokines & Chemokines

TNF-α, IL-1, IL-6, IL-8

Coordinate immune cell activation, fever response, and chemotaxis

Plasma-derived mediators

Complement proteins, Kinins

Enhance opsonization, promote vascular permeability, and attract neutrophils

Reactive species

Nitric oxide, Reactive oxygen species

Modulate vascular tone, kill pathogens, but can also cause tissue damage

Neuropeptides

Substance P

Influence pain perception and vascular changes

Key Roles in Inflammation

• Initiation: Detect harmful stimuli and trigger the inflammatory cascade.

• Amplification: Recruit and activate more immune cells.

• Resolution: Help switch off inflammation once the threat is neutralized.

• Repair: Promote tissue healing and regeneration.

Why They Matter

While essential for defense, excessive or uncontrolled release of inflammatory mediators can lead to chronic inflammation and contribute to diseases such as asthma, rheumatoid arthritis, and cardiovascular disorders.

Would you like me to break down specific mediators one by one (e.g., histamine, prostaglandins, TNF-α) with their detailed mechanisms, or keep it at this broader overview?

What Rheumatoid Arthritis Is?

Rheumatoid arthritis (RA) is a chronic autoimmune disease where the immune system attacks the lining of the joints. This causes inflammation, pain, stiffness, and swelling. Over time, it can damage cartilage and bone, leading to deformities and loss of function.

Key Features

• Autoimmune nature: The body’s defense system mistakenly targets healthy tissue.

• Commonly affected joints: Hands, wrists, knees, ankles, and feet.

• Symptoms: Persistent joint pain, morning stiffness, fatigue, and sometimes fever.

• Systemic impact: RA doesn’t just affect joints—it can involve the heart, lungs, eyes, and blood vessels.

RA Compared to Osteoarthritis

RA is different from osteoarthritis (OA). RA is driven by the immune system and often affects both sides of the body symmetrically, while OA is caused by wear-and-tear and usually affects one joint more than the other. RA can strike at younger ages, whereas OA is more common in older adults.

Diagnosis and Management

Doctors use blood tests (like rheumatoid factor and anti-CCP antibodies), imaging scans, and physical exams to confirm RA.

• Medications: DMARDs, biologics, corticosteroids, and NSAIDs.

• Lifestyle: Regular exercise, balanced diet, and stress management.

• Therapies: Physical and occupational therapy to maintain mobility.

• Surgery: Joint replacement in severe cases.

Why Early Treatment Matters

If left untreated, RA can cause irreversible joint damage and increase the risk of cardiovascular disease. Early diagnosis and treatment are crucial to slow progression and preserve quality of life.