TBPP_Immunoglobulin

joined by J-chain (protein), f.e. pentameric IgM (with J-chain), hexameric IgM (without J-chain), dimeric IgA (50% in the body, the rest monomeric, with J-chain), secretory IgA (with J-chain and secretory component, more stable)

ribbon structure, used in all Ig's, building blocks, for IgG1: 2xVL, 2xCL, 2xVH, 2xCH1, 2xCH2, 2xCH3 and hinge-region, IgM and IgE: 4 CH-domains, IgG and IgA: 3 CH-domains

treatment with papain: Fab and Fc, treatment with pepsin: F(ab')2 and peptide fragments, special effector functions for therapeutical use (f.e. Fab in Lucentis, prevents tumours from growth)

antigen, C3a, C3b, FcyR, FcRn, CDR

large amount of variability caused by V-D-J rearrangement (changes in parts of light and heavy chain, different combinations)

hypervariable stretches in VL and VH chains, responsible for specific contact to antigens, can be edited to increase binding affinity, create a shape putting AS together

IgG most abundant of Ig's, longest half life (21 days), IgD and IgE in lowest amounts available

most abundant plasma Ig, arises after isotype switch from IgM, fab function: binds antigens, fc function: mediate effector mechanisms by engaging FcyRs and others, effector functions are subclass-dependent

second most abundant plasma Ig, 90% monomeric, 10% dimeric, fab function: bind antigens (same recognition pattern like IgG but at lower level), fc function: limited via. Fc?R, the non-inflammatory isotype (ITAMI signalling?), role of IgA somewhat enigmatic, secretory IgA: secretion onto mucosal surfaces, neutralisation of pathogens, interactions with microbiota and food, allow food and colonizing microbes but "find" them, limited cross-talk between central and mucosal IgA

third most abundant plasma Ig, first isotype, Fab function: bind antigens, fc function: strong ability of C' activation: antibacterial immunity and shaping antibody repertoire

low amounts, fab function: binds antigens, often allergens, Fc function: strong ability to activate Fc?R+ cells (basophils, eosinophils, mast cells), defense against helminths and other protozoans, more frequently in super-clean western society: allergy

Fab: depending on AS sequence in CDRs, Asn 297: complex type, essential for Fc conformation and IgG stability, modulation of effector functions, Sialic acid: anti-inflammatory properties, galactose: for high affinity C1q and FcyR binding, GlcNac, mannose, fucose: removal enhancers, affinity from FcyRIIIA to ADCC

fucose affects antibody binding from FcyRIIIa to ADCC, lysis of tumour cells by NK cells with defucosylated recombinant mAbs, glyco-engineering of expression cell lines

intravascular (IVIG): very high increase with higher dose, direct injection to the central compartment, extravascular (SCIG): more frequently injections but with lower doses. Reason for the longest half-lives: protection from degradation by FcRn binding, industrial application: prolong half-life by fusion to IgG-Fc or albumin, blockade of FcRn?

bases of industry: blood transfusion and passive immunization (Behring and Kitasato: passive immunization with horse plasma, Bruton: agammaglobulinaemia and IgG therapy, Imbach: first use of IVIG in autoimmune indication.

1. IgG concentrates: intra-muscular injection because of aggregates, destruction of effector functions. 2. hyper-purified non-modified IgG: deaggregated, first i.v. compatible preparations but with low grade of pepsin (no protein activity). 3. combination of ethanol with other fractionations: IV, prevention of aggregation, from lyophilyzed to liquid stable products

ethanol-fractionation --> elimination of impurities (octanoic acid) --> virus inactivation (at low pH) --> depth filtration (elimination impurities/viruses) --> IEX chr. (polishing) --> virus filtration --> formulation (stabilization, concentration) --> filling --> visual inspection --> packaging

always 3. generation production, different stabilizers used (sorbitol, glycine, L-proline), 3 important enterprises: grifols, baxalta/shire, CSL Behring

increased use, lower trough levels than IV, more flexible dosing, home administration, simplifying application, patient convenience, various s.c. immunoglobulin products depending on the enterprise

anti-rhesus D: if the father is Rh+ and mother Rh-: dangerous for the second child because of the antibodies-attack against Rh+ child, antibodies removed with rhophylac preventing immunization, source of plasma: hyperimmunization of RhD- men with RhD+ erythrocytes. / for specific applications: cytomegalovirus for prevention of CMV transmission in solid organ, tetanus, diphteria, rabies, Hep. B, Australian CSL: anti-venoms

Fab dependent: blocking receptors, neutralization, cytokine and complement inhibition, anti-idiotypes, in immunodeficiency. Description of agammaglobulinaemia and replacement therapy, famous case: "the boy in the bubble" = Primary immunodeficiency (PID): most common: IgA deficiency (minor symptoms), wiscott-aldrich syndrome, common variable immuno-deficiency, X-linked agammaglobulineamia, disruption of B-cell formation. alternatives to IVIG: bone marrow transplantation, gene therapy?, recombinant IVIG?, IVIG labelled for some secondary immunodeficiencies.

Fc dependent: blocking Fc-receptors, complement inhibition, FcRn saturation, anti-inflammatory therapy in auto-antibody mediated diseases, immune thrombocytopenia (ITP): auto-abs against platelets, leading to bleeding disorder, due to secondary immunodeficiency, studies in bern (Imbach). CIDP: auto-antibody mediated neurological disease, waekness, numbness, pain, symmetrical, sometimes presence o anti-ganglioside autotabs, IVIG first line treatment,

nebulized Ig for lung nfection

manufacture of IVIG highly technical requiring specialized facilities, supply dependent on availability of human plasma, product has some natural variability, large doses needed to be applied. Need to produce key efficacy mechanisms of IVIG at lower doses

anti-inflammation: multimerized Fc molecules or monoclonal antibodies that mimic a single effector mechanism of IgG, Gliknik/Stradomer: IgG2 hinge region for dimerisation, heterogenous product, 100-fold lower dose than IVIG. Diversity of multimeric Fc structures. Hexagard: heterogenous product, mix of hexamer and dimer (IgG1-Fc and 18 AS of IgM). Other approaches: interference with Fc receptors: increased binding to FcRn, with mutated Fc fragments or anti-FcRn monoclonals