Immunology

Immunology examines immune system physiology, inflammatory signaling pathways, hypersensitivity reactions, and pharmacologic modulation of immune responses.

This section progresses from immune physiology → inflammatory mediators → hypersensitivity → immune-targeting pharmacology → clinical disease integration.

Immunology underlies:

• Allergic Rhinitis
• Anaphylaxis
• Asthma
• Inflammatory Bowel Disease
• Rheumatoid Arthritis
• Psoriasis
• Sepsis
• Transplant Rejection

• Innate immunity initiates inflammation.
• Adaptive immunity provides specificity and memory.
• Th1/Th17 drive autoimmune inflammation.
• Th2 drives allergic disease.
• COX pathway → prostaglandins.
• 5-LOX pathway → leukotrienes.
• NSAIDs block COX.
• COX-2 inhibitors selectively block inflammatory COX-2.
• Leukotriene modifiers block bronchoconstrictive leukotrienes.
• Corticosteroids suppress upstream inflammatory transcription.
• Biologics target specific cytokines.

• Innate Immunity
• Complement System
• Leukocyte Recruitment & Chemotaxis
• Cytokines Overview

Major innate mediators:

• TNF-α
• IL-1 / IL-6
• Type I Interferons

• Adaptive Immunity
• Antigen Presentation & MHC
• T Cell Activation
• B Cell Activation & Class Switching
• T Helper Subsets
• Immunoglobulin Classes

Dominant T-helper patterns:

• Th1 → Rheumatoid Arthritis
• Th2 → Allergic Disease / Asthma
• Th17 → Psoriasis / IBD
• Treg → immune tolerance

Membrane phospholipids → Phospholipase A2 → Arachidonic Acid →

→ COX pathway → Prostaglandins & Thromboxanes

→ 5-Lipoxygenase Pathway → Leukotrienes

Phospholipase A2 blockade:

• Corticosteroids

Used in:

• Asthma
• IBD
• Rheumatoid Arthritis
• Psoriasis

• NSAIDs
• Aspirin

Used in:

• Rheumatoid Arthritis
• Inflammatory pain conditions

• COX-2 Inhibitors

Used in:

• Rheumatoid Arthritis
• Osteoarthritis

• Misoprostol
• Alprostadil
• Latanoprost

Drug modulation:

• Leukotriene Modifiers

Used in:

• Asthma
• Allergic Rhinitis

Drug modulation:

• First Generation Antihistamines
• Second Generation Antihistamines
• Corticosteroids
• Epinephrine

Used in:

• Allergic Rhinitis
• Anaphylaxis

Drug Modulation

• Complement Inhibitors

• Corticosteroids
• Methotrexate
• Azathioprine
• 6-Mercaptopurine

Calcineurin inhibitors:

• Calcineurin Inhibitors

Used in:

• Transplant Rejection
• Autoimmune disease

Anti-TNF Agents

• Infliximab
• Adalimumab
• Etanercept
• Certolizumab
• Golimumab

Anti-IL-12/23 Agents

• Ustekinumab

IL-23 Inhibitors

• Guselkumab
• Risankizumab
• Tildrakizumab
• Mirikizumab

IL-17 Inhibitors

• Secukinumab
• Ixekizumab
• Brodalumab
• Bimekizumab

IL-6 Inhibitors

• Tocilizumab
• Sarilumab
• Siltuximab

IL-1 Inhibitors

• Anakinra
• Canakinumab
• Rilonacept

Anti-IgE Agents

• Omalizumab

Anti-Integrin Agents

• Vedolizumab
• Natalizumab

JAK Inhibitors

• Tofacitinib
• Baricitinib
• Upadacitinib
• Filgotinib (non-US approval varies)
• Ruxolitinib

Complement Inhibitors

• Eculizumab
• Ravulizumab
• Avacopan
• Pegcetacoplan

Costimulation Blockers

• Abatacept