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Lymphocytes - Coggle Diagram

- - - - Plasma cell secrete
        
        Antibodies bind
        
        encoded by
        
        Igλ gene
        
        encodes light chain λ
        
        IgH gene
        
        encodes heavy chain
        
        has 4 major regions
        
        Variable (V)
        
        Diversity (D)
        
        Joining (J)
        
        Constant (C)
        
        Igκ gene
        
        encodes light chain κ
        
        Antigens
        
        soluble antigen
        
        bound antigen
        
        every antibody has:
        
        2 Heavy chains
        
        variable region: determines binding specificity for antigen
        
        constant region: determines class of antibody
        
        2 Light chains
        
        variable region: determines binding specificity for antigen
        
        constant region: can be kappa (κ) or lambda (λ) same
        
        5 Classes
        
        IgA
        
        IgD
        
        IgE
        
        IgG
        
        IgM
      - Memory Cell
      - Somatic Hypervariability: genes purposefully mutated w/in variable region to give more possible outcomes
        
        Activation-Induced Cytidine Deaminase (AID protein): changes single nucleotide w/in variable region during hypervariability
        
        class-switching: DNA recombined to form different isotopes of constant region
        
        Uracil-DNA-Glycosylase (UNG protein): takes out base in S region marked by AID
  - - - <---
        
        pro B cell
        
        <---
        
        pre B cell
        
        <---
        
        immature B cell
        
        3 more items...
        
        light chain gene recombination
        
        if no functional light chain created cell undergoes apoptosis
        
        heavy chain gene recombination
        
        heavy chain must form pre-B cell receptor with surrogate light chain to change from pro-B cell to pre-B cell
  - - - Phase III (Positive Selection)
        
        Phase IV
        
        Phase V
        
        in secondary lymphoid tissue
        
        activation of B cells after antigen binding
        
        Phase VI
        
        in secondary lymphoid tissue
        
        differentiation into Plasma/Memory cell
        
        in lymph/blood/secondary lymphoid tissue
        
        mature B cells circulate to find pathogens
        
        in secondary lymphoid tissue
        
        attracted to lymph nodes by CCL21
        
        CCR7 on B cells recognizes and binds CCL21
        
        immature to mature B cells
        
        immature B cells now in circulation
      - in bone marrow
      - removes B cells that bind to "self" cells
        
        defective cells undergo apoptosis
        
        self-antigens are molecules on human tissue
        
        self-reactive receptors are receptors on B/T cells that bind self-antigens
        
        if immature B cell binds self-antigen on bone marrow cell, RAG proteins activated to edit further
        
        if B cell binds soluble self-antigen, anergy occurs
        
        anergy: B cell inactive, alternative splicing activated to make mostly IgD instead of IgM
        
        B cells containing high IgD cannot be activated by phase III
- - - - both have variable and constant region
      - alpha/beta require MHC on self cells for activation
      - gamma/delta can sometimes be activated without MHC
    - - Antigen Presenting Cell (APC): any cell that presents an antigen using MHC
      - MHC Class I: also found on professional APC
        
        presents intracellular pathogen antigens from viruses
        
        found on most cell types
        
        recognized by TCR and CD8 on cytotoxic T cells
      - MHC Class II: only on professional APC
        
        presents extracellular pathogen antigens from bacteria/fungi/parasites
        
        recognized by TCR on CD4 on helper T cells
        
        invariant chain: acts as chaperone for MHC II
  - - - CD34 stem cell enters thymus becomes double-negative T cell, expresses neither CD4 or CD8
      - double-positive thymocyte expresses both CD4 and CD8
        
        Pre-T-cell receptor: expressed on double-positive T cell
    - - positive selection of only T cells that bind MHC
      - if unable to bind, TCR can try for 3-4 days before apoptosis
      - single-positive T cell: only expresses CD4 OR CD8
    - - negative selection of T cells that bind "self" antigens
      - occurs mainly in medulla of thymus
      - Autoimmune Regulator (AIRE): transcription factor that allows expression of tissue-specific proteins from other organs
    - - Treg: regulatory T cells that suppress CD4
        
        have CD25 surface protein as well as CD4