Immunogenomics

• B-Cells
  • B-Cells recognize non-body stuff, which are called antigen by either recognizing it with receptors on their cell membrane or by secreting these receptors in the form of antibodies.
  • B-Cell Proteins
    • An Antibody comes in five different flavors (in placental mammals) IgA, IgD, IgE, IgG, IgM. They all share the same basic structure, but differ in their additions. Somehow we assume that IgG is the most important, because it is the most common type and we don't know that much about the other types anyways.
    • IgG is one of those antibody types that looks like a Y. The *ends* of the arms of the Y recognize the antigen, the *ends* not the middle part.
    • All antibodies, and so IgG are composed of two identical Heavy and two identical Light Chains
    • The two ends of the Y, the part that recognizes the antigen are together called Fab. One Fab comprises a bit of the heavy chain and a bit of the light chain. Not everything touches the antigen, so the most important region in the Fab fragment is called Fv (variable).
    • The Fv can be split into its three main parts, the [complementary determining regions], called CDR1, CDR2 and CDR3. Remember that there is a light and a heavy chain in one Fv, so there are six complementary determining regions in total.
  • B-cell genomes
  • B-cells are one of the very few cells that can do somatic recombination with their genome

• • Somehow we think that the heavy chains are more important than the light chains, and CDR3 more important than CDR1 and CDR2

• • The heavy chains are encoded by one of the few loci that can recombine somatically, the IGH-locus