II. Definitions

  1. Fragment Antigen Binding (Fab)
    1. Antibody region that recognizes and binds antigens
  2. Fragment Crystallizable (Fc)
    1. Antibody region that interacts with Immune System components
    2. Endogenous Fc triggers Natural Killer Cells and complement cascade
    3. Synthetic monoclonal antibodies may bind Fc to toxins or radioisotopes in Chemotherapy
  3. Ligand
    1. Molecule that binds to a specific receptor
  4. Humoral Immunity
    1. Humoral Immunity (i.e. B-Cells and antibodies) targets extracellular pathogens
    2. Part of Adaptive Immunity (learned Immunity) in combination with cellular Immunity (T-Cell function)

III. Physiology: B-Cells

  1. Derivation
    1. Fetal Liver
    2. Bone Marrow Pluripotent Stem Cells
  2. Peripheral Migration to Secondary Lymphoid Tissue
    1. Spleen
    2. Lymph Nodes
    3. Peyer's Patches (Small Bowel)
  3. Activation
    1. Recognition
      1. Antigen binds B-LymphocyteSurface Receptor (BCR)
      2. BCR binding activates B-Lymphocyte
        1. T-Cell Independent Antigen (e.g. inert antigens) alone activate B-Cells
        2. T-Cell Dependent Antigen (e.g. microbes) require added stmulus (e.g. T Cells)
    2. B-Cell Proliferation
      1. Activated Lymphocytes proliferate
    3. B-Cell Differentiation
      1. Plasma Cells (Antibody producing cells)
        1. Survive for days to weeks producing antibodies, and without replicating
      2. Memory Cells
        1. Remain in B-Lymphocyte pool ready to respond to the same antigen in future
        2. Future antigen response is known as secondary immune response

IV. Physiology: Immunoglobulin

  1. Images
    1. idAntibody.jpg
  2. Immunoglobulins (or antibodies) are Y-Shaped glycoproteins generated by Plasma Cells
  3. Immunoglobulin is composed of a 4 chain monomeric structure
    1. Two heavy chains (identical)
      1. Five heavy chain classes: M, D, E, A, and G1-4
    2. Two light chains (identical)
      1. Two light chain classes: kappa and lambda
  4. Immunoglobulin stem (Fc) is composed of 2 identical heavy chains
  5. Two Immunoglobulin Arms emanate from the stem
    1. Each arm is composed of 2 heavy chains and 2 light chains
    2. The end of each arm contains an antigen binding site (Fab)
  6. Immunoglobulins have 2 forms
    1. Membrane bound Immunoglobulins (on surface of B-Cell)
    2. Secretory Immunoglobulin (unbound, free-floating)
      1. Monomeric antibodies exist as single Antibody molecules (IgE or IgG)
      2. Multimeric antibodies exist as multiple joined antibodies (IgA or IgM)
        1. Connected with J Chains
    3. Antibodies
      1. Immunoglobulin (Ig)

V. Types: Immunoglobulins

  1. Immunoglobulin G (IgG and subclasses IgG1-4)
    1. Monomer with Molecular weight 160,000 dalton
    2. Accounts for 75% of all Antibody
    3. Serum half-life of 23 days
    4. Responsible for long lasting Immunity (secondary immune response) and Type 2 Hypersensitivity
  2. Immunoglobulin A (IgA and subclasses IgA1, IgA2)
    1. Dimer (2 Antibody molecules) when secretory Ig with Molecular weight 350,000 dalton
    2. Accounts for 10-15% of all Antibody
    3. Serum half life of 6 days
    4. Present in body secretions (e.g. tears, Saliva, milk) and responsible for mucosal Immunity
  3. Immunoglobulin M (IgM)
    1. Pentamer (5 Antibody molecules) when secretory Ig with Molecular weight 900,000 dalton
    2. Responsible for early, primary Antibody response
  4. Immunoglobulin E (IgE)
    1. Long stem (Fc) monomeric Antibody with Molecular weight 180,000 dalton
    2. Serum half-life of 2.5 days
    3. Reacts to allergans (Type 1 Hypersensitivity) and Parasitic Infections
  5. Immunoglobulin D (IgD)
    1. Monomer with Molecular weight 160,000 dalton
    2. Serum half life of 3 days
    3. Membrane bound surface Antibody

VI. References

  1. Bakerman (1984) ABCs of Interpretive Lab Data, p. 392
  2. Mahmoudi (2014) Immunology Made Ridiculously Simple, MedMaster, Miami, FL

Images: Related links to external sites (from Bing)

Related Studies

Ontology: Antibodies (C0003241)

Definition (NCI_NCI-GLOSS) A protein made by plasma cells (a type of white blood cell) in response to an antigen (a substance that causes the body to make a specific immune response). Each antibody can bind to only one specific antigen. The purpose of this binding is to help destroy the antigen. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy the antigen.
Definition (NCI) A type of protein made by B lymphocytes in response to a foreign substance (antigen). Each antibody only binds to a specific antigen, helping to destroy the antigen directly or by assisting white blood cells to destroy the antigen.
Definition (CSP) infection-fighting protein molecule in blood or secretory fluids that tags, neutralizes, and helps destroy pathogenic microorganisms such as bacteria or viruses and toxins; they are generally known as immunoglobulins, and are made and secreted by B-lymphocytes in response to stimulation by antigens; each specific antibody binds only to the specific antigen that stimulated its production.
Definition (MSH) Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).
Concepts Immunologic Factor (T129) , Amino Acid, Peptide, or Protein (T116)
MSH D000906
SnomedCT 68498002
LNC LP39213-1, LP17809-2, LP20667-9, LP17807-6, LP38951-7, LP40096-7, MTHU003502, MTHU001898, MTHU003494
English Antibodies, Antibodies [Chemical/Ingredient], antibody, antibodies, Unidentified Ab, Little NOS Ab, NOS Ab, Unidentified Antibody, not otherwise specified Antibody, Little not otherwise specified Antibody, Antibody, Antibody (substance), Antibody, NOS, Ab
Swedish Antikroppar
Czech protilátky
Finnish Vasta-aineet
Latvian Not Translated[Antibodies]
Polish Przeciwciała
Norwegian Not Translated[Antibodies]
Spanish anticuerpo (sustancia), anticuerpo, Anticuerpos
French Anticorps
German Antikörper
Italian Anticorpi
Portuguese Anticorpos

Ontology: Humoral Immunity (C0020967)

Definition (MSH) Antibody-mediated immune response. Humoral immunity is brought about by ANTIBODY FORMATION, resulting from TH2 CELLS activating B-LYMPHOCYTES, followed by COMPLEMENT ACTIVATION.
Definition (NCI) Immune processes mediated by antibodies
Definition (CSP) immunity mediated by antibodies.
Concepts Organism Function (T040)
MSH D056724
English Immunity, Humoral, humoral immunity, Humoral Immune Response, Humoral Immunity
French Immunité humorale
German Humorale Immunität, Immunität, humorale
Italian Immunità umorale
Portuguese Imunidade Humoral
Spanish Inmunidad Humoral
Czech imunita humorální, imunita protilátková
Swedish Immunitet, humoral
Polish Odporność humoralna
Norwegian Humoral immunitet

Ontology: Ligands (C0023688)

Definition (NCI) An ion, molecule or molecular group that binds to a substance to form a larger complex.(Dr. Joseph A. Thie)
Definition (MSH) A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)
Definition (CSP) molecule that binds to another molecule, especially a small molecule that binds specifically to a larger molecule.
Concepts Chemical (T103)
MSH D008024
French Ligands
Swedish Ligander
Czech ligandy
Finnish Ligandit
Croatian LIGANDI
English ligand, ligands, Ligand, Ligands
Polish Ligandy, Addenty
Spanish Ligantes, Ligandos
German Liganden
Italian Ligandi
Portuguese Ligantes