Molecular Structure and Composition:

• Calcium and zinc-binding protein complex
• Composed of two subunits:
• S100A8 (MRP8/Calgranulin A)
• S100A9 (MRP14/Calgranulin B)
• Belongs to S100 protein family
• Forms heterodimers/heterooligomers
• 24 kDa molecular weight
• Stable against temperature and proteolysis

Biological Functions and Distribution - Cellular Sources:

• Primarily expressed in:
• Neutrophils (60% of cytosolic proteins)
• Monocytes
• Early macrophages
• Inflamed epithelial cells

Key Functions:

• Antimicrobial Activity:
• Sequesters metal ions
• Creates nutrient-limited environment
• Direct antimicrobial properties
• Inflammatory Response:
• Acts as DAMP
• Activates TLR4
• Promotes inflammatory cytokines
• Recruits leukocytes

Clinical Applications - Diagnostic Marker:

• Used in various conditions:
• Inflammatory Bowel Disease (IBD)
• Rheumatoid arthritis
• Cancer progression
• Cardiovascular disease
• Neonatal sepsis
• Laboratory Testing:
• Non-invasive
• High sensitivity/specificity
• Stable at room temperature
• Cost-effective screening

Pathological Implications:

• Associated with:
• Gastrointestinal Disorders
• Systemic Conditions
• Rheumatoid Arthritis
• Lupus
• Cancer

Current Research and Future Perspectives:

• Active research areas:
• Improved detection methods
• Novel therapeutic targets
• Cancer biology role
• Personalized medicine
• Microbiome regulation
• Applications in:
• Disease diagnosis
• Treatment monitoring
• Drug development
• Prognostic evaluation