Adaptive Immune Response PDF

Adaptive Immune System Chapters 11 and 12 Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar...

Adaptive Immune System Chapters 11 and 12 Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  Introduction Antigens and Antibodies Lymphocytes Clonal selection and expansion Outline Lymphocyte stimulation Antibody production Cytokines Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  Microbes can overcome innate IR and cause infections Adaptive response against such microbes Specific for a given organism Memory Faster, bigger response if the same microbe encountered the second time Two types Introduction Antibody-mediated Cell-mediated. Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar Integration of Adaptive and Innate IR Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  Antigen ‘Antibody generator’ New definition Any molecule that reacts specifically with Ab or Ag receptor on lymphocyte Immunogen Ag that can induce IR Antigenic/immunogenic Antigens Relative ability of Ag to elicit IR Antigenic determinants = epitopes Discreet region(s) of Ag molecule specifically recognized by adaptive IR E.g. stretch of 10 or more aa E.g. 3-D structure/protrusion in a molecule Antigenic structure Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  Antibody Antibody- Produced by B-lymphocytes = B cells (develops in Bursa of birds, bone marrow in humans) mediated Neutralizes free-floating particles (bacteria, toxins, free viruses) (Humoral) In response to extracellular Ag, B cells triggered to proliferate and differentiate into plasma cells Immunity Y-shaped proteins called Abs Some B-cells form memory cells © Ayush Kumar  Two functional regions 2 identical arms and 1 stem Arms – bind to specific antigen Stem – tags antigen for destruction by other IS components Antibody Structure Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  Light chain Two types based on amino acid sequence of the constant regions λ and κ A given B cell will produce Ab of only one specificity Both L chains are identical, so either both will be Lλ or both Lκ Heavy Chain Five types based on aa sequence of the constant region, gives Types of the ‘class’ of the antibody type μ = IgM γ = IgG Antibodies α = IgA δ = IgD ε = IgE Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  IgG Makes up 75% of serum immunoglobulins Has basic monomeric structure Four subclasses based on amino acid sequence of the C regions of H chains: IgG1, IgG2, IgG3, IgG4 IgG1 is most prevalent Classes of Functions Antibodies Opsonization Neutralizes viruses and toxins Main Ab type made in secondary response, when body encounters Ag for second and subsequent times Crosses placenta – passive immunity for fetus from mother Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  IgM Monomeric, when attached to B cell surface as a receptor Pentameric in serum, 5 monomers held together Classes of by a J chain Functions Antibodies First Ab class produced during primary response Ag receptor on B cells Activates part of innate defences Agglutinates particulate Ag, e.g. bacteria http://www.medicine.mcgill.ca/physio/vlab/immun/backg.htm Do not distribute this file without permission from Dr. Ayush Kumar ©Ayush Kumar © Ayush Kumar  IgD Monomeric form Classes of Found in serum and on B cell surface as receptor Antibodies Very low amounts,