Review: Cells of the Immune System Leukocytes– White blood cells Myelocytes–macrophage, neutrophil, eosinophil,basophil Leukocytes – B, T and NK cells From Larsson and Karlsson (2005)
Review: Cells of the Immune System Larsson and Karlsson (2005)
Review: Myelocytes Dendritic cell
Review: Myelocytes •Macrophages – phagocytes, antigen presenting cells (APCs), specialized cells different organs, secrete cytokines, produce complement proteins, can produce ROS/RNS. •Neutrophils – phagoctyes, can produce ROS/RNS, secrete antimicrobial peptides, 1st cell type to migrate from blood to infections, main targets are bacteria and fungi •Eosinophils– phagocyte, targets parasites •Basophils – secrete cytokines, involved in allergic response
Review: Lymphocytes Lymphocytes: T cells B cells Natural killer cells
Review: Lymphocytes • B cells – naïve B cells: contain antigen binding receptor (or membrane bound antibody), once activated – memory cells: provides memory of antigen/antibody interaction; plasma cells: secrete soluble antibody
Review: Lymphocytes • T cells - contain antigen binding receptor (TCR) THcells: secretes cytokines that activate B cells, TCcells, macrophages and others. TCcells: eliminates altered/damaged self cells (particularly those infected by viruses), fights tumors cells, secrete cytotoxins. Tregcells: helps suppress immune response, plays a role in tolerance. T reg cell
Review: Cells of the Immune System •Natural killer cells – distinct from T and B cells due to lack of an antigen binding receptor, similar in function to TCcells, macrophage activation, defense against viruses, fight tumor formation, secrete cytotoxins.
Review: Cells of the Immune System Derived from both lymphoid and myeloid precursors •Dendritic cells – phagoctyes, antigen presenting cells (APCs), can produce ROS, secrete proinflammatory cytokines, secrete antimicrobial peptides.
Review: Organs of the Immune System Primaryand secondary lymphoid organs: 1°- maturation of lymphocytes 2°- sites where mature lymphocytes interact with antigen. Level of organization: collection of cells vs. lymphoid follicle
Review: Adaptive Immune Response Antigen/Antibody interactions: Antigen – any substance that binds specifically to an antibody or a T cell receptor (TCR). Antibody- a protein (immunoglobulin) that recognizes a specific region (component) of an antigen. Properties of immunogenicity: Foreignness Molecular size Chemical composition/complexity Processing/presentation Host factors Dosage Route of entry
Antibody-Mediated Effector Functions Opsonization Assist/activate complement system ADCC
Humoral and Cellular Immunity •Humoral immunity – Host defenses that are mediated by antibody present in the plasma, lymph and tissue fluids. •Cellular immunity – Host defenses that are mediated by antigen-specific T cells and various nonspecific cells of the immune system.
The Complement System Ricklin and Lambris 2007
The Complement System Functions of the Complement System
The Complement System Components of the Complement System: proteins and glycoproteins synthesized mainly by liver 5% of serum circulate as zymogens Designation of complement components: numerals (C1-C9) letter symbols (factor D) trivial names (homologous restriction factor) cleavage products – “a” and “b”
The Complement System Complement Activation Pathways: Classical Pathway Alternative Pathway Lectin Pathway