Immune Responses and Soluble Molecules

Immune Responses and Soluble Molecules

• Soluble molecules play critical roles in both innate and adaptive immune responses.

Innate Immune Responses

• Cytokines: Include interleukins (IL) and interferons (IFN), signaling proteins that mediate immune responses.
• Antimicrobial Peptides:
  • Target and eliminate microbes or inhibit their reproduction.
  • Defensins are key examples, categorized into α-defensins and β-defensins, known for disrupting microbial membranes and inhibiting RNA, DNA, and protein synthesis.
  • Primarily produced by neutrophils and epithelial cells.
• Complement System: Consists of proteins that enhance the ability of antibodies and phagocytic cells to clear microbes.
• Pattern-Recognition Receptors (PRRs):
  • Detect unique antigens in microorganisms.
  • Types include membrane-bound (e.g., Toll-like receptors, C-type lectin receptors) and cytoplasmic receptors (e.g., NOD-like receptors, RIG-I-like receptors).

Pattern-Recognition Receptors (PRRs)

• Function:
  • Recognize non-self antigens (PAMPs and DAMPs).
  • Activate immune responses, including opsonization, complement activation, phagocytosis, pro-inflammatory signaling, and apoptosis.
• PAMPs (Pathogen-Associated Molecular Patterns): Associated with microbial pathogens, these patterns signal the presence of potential threats.
• DAMPs (Damage-Associated Molecular Patterns): Released by host cells during damage, indicating cell stress or death.

Toll-Like Receptors (TLRs)

• A subset of PRRs, these proteins are essential for detecting microbial components post-barrier breach.
• Found on various immune and non-immune cells, including dendritic cells, macrophages, and epithelial cells.
• Recognize structurally conserved microbial molecules, leading to immune activation.
• Structure: Comprises exterior leucine-rich repeats (LRRs) and an interior TIR (Toll-IL-1 Receptor) domain.
• Types: Includes TLR1 to TLR13, with TLR11-13 not present in humans.

NOD-Like Receptors (NLRs)

• Cytoplasmic PRRs that detect both PAMPs and DAMPs.
• Participate in signal transduction and share structural similarities with TLRs.
• Comprise 23 family members, characterized by three domains: LRR, NACHT, and effector binding (EBD).

C-Type Lectin Receptors (CLRs)

• Surface receptors found on various immune cells: monocytes, macrophages, dendritic cells, etc.
• Recognize carbohydrate components from fungi, bacteria, viruses, parasites, and allergens.
• Major human CLRs include receptors for mannose, fucose, and glucans, facilitating immune signaling and phagocytosis.

Explore the diverse types of biologically active soluble molecules involved in both innate and adaptive immune responses. This quiz covers key elements such as cytokines, antibodies, and complements, and their roles in immunity. Test your knowledge on how these molecules contribute to our body's defense mechanisms.