Review: Cells of the Immune SystemLeukocytes – 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

Lymphocytes:

T cellsB 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)TH cells: secretes cytokines that activate B cells, TC cells,

macrophages and others.TC cells: eliminates altered/damaged self cells (particularly

those infected by viruses), fights tumors cells, secrete cytotoxins.Treg cells: helps suppress immune response, plays a role in

tolerance.

Review: Lymphocytes

T reg cell

•Natural killer cells – distinct from T and B cells due to lack of an antigen binding receptor, similar in function to TC cells, 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: Cells of the Immune System

Review: Organs of the Immune SystemPrimary and 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: Innate and adaptive immunity

Review: Innate Immune Response

Review: Adaptive Immune ResponseAntigen/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:ForeignnessMolecular sizeChemical composition/complexityProcessing/presentationHost factorsDosageRoute of entry

Antibody-Mediated Effector FunctionsOpsonizationAssist/activate complement systemADCC

Humoral and Cellular Immunity

•Cellular immunity – Host defenses that are mediated by antigen-specific T cells and various nonspecific cells of the immune system.

•Humoral immunity – Host defenses that are mediated by antibody present in the plasma, lymph and tissue fluids.

The Complement System

Ricklin and Lambris 2007

The Complement SystemFunctions of the Complement System

The Complement SystemComponents of the Complement System:

proteins and glycoproteinssynthesized mainly by liver5% of serumcirculate 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 SystemComplement Activation Pathways:

Classical PathwayAlternative PathwayLectin Pathway