Cells of the Immune System

Cells of the Immune System

1. Leukocytes (white blood cells)

   • Small lymphocyte
     • Production of antibodies (B cells) or cytotoxic and helper functions (T cells)
   • Natural killer cell
     • Kills cells infected with certain viruses
   • Plasma cell
     • Fully diferentiated form of B cell that secreted antibodies
   • Dendritic cell
     • Activation of T cells and initiation of adaptive immune response
     • Sessile dendritic cells
       • Contact with external environment e.g. skin
   • Neutrophil
     • Phagocytosis and killing of microorganisms
     • Large range of receptors that mediate recognition and phagocytosis
       • Pattern recognition receptors (PRRs) that detect microbial associated molecular patterns (MAMPs)
         • Toll-like receptors (TLRs)
         • NOD-like receptors (NLRs)
         • RIG-I-like receptors (RLRs)
         • Other cytosolic nucleic acid sensors
         • C-type lectin receptors (CLRs)
       • Receptors that detect signalling proteins e.g. cytokines
       • Peptidoglycan recognition proteins (PGRPs)
         • Some are lymphocyte surface associated
         • Some are intracellular
         • Some are circulating
         • Recognise, opsonise and some may be directly antimicrobial
     • Can make alpha-defensins
       • Pore forming peptide antibiotic
   • Basopohil
     • Unknown
   • Eosinophil
     • Killing of antibody-coated parasites through release of granule contents
   • Mast cell
     • Expulsion of parasites from body through release of granules containing histamine and other active agents
   • Monocyte
     • Circulating precursor cell to macrophage
   • Macrophage
     • Phagocytosis and killing of microorganisms. Activation of T cells and initiation of immune response
     • Motile mactrophages
       • Patrol tissues acting as a first line of defence
       • Act as scavengers that rid the body of worn-out cells and other debris
     • Subcategorised depending on anatomical location
       • Alveolar (lungs)
       • Osteoclasts (bone)
       • Microglia (brain)
       • Kupffer cells (liver)
     • Have receptors that can talk to T-cells and mediate adaptive immunity

2. Lymphocyte

   • Travel via the lymphatic system
   • Lymph nodes act as sites of communication between lymphocytes

3. Use confocal microscopy and staining to study cells

   • Green fluorescent protein (GFP)

4. Recognition by lymphocyte

   • Acid
   • Toxic oxygen derivatives
   • Peptides and proteins
   • Enzymes
   • Competitors