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#antibodies

22 public questions tagged with this topic.

Abzymes are antibodies that:

Catalytic antibodies termed abzymes represent attempt to harness immune binding energy for chemical transformation similar to enzymes that accelerate reactions 10^10 fold by stabilizing transition state through complementarity. Natural enzymes use preorganized active site residues histidine, aspartate, serine triad precisely positioned via folding to provide general acid-base, nucleophile, oxyanion hole stabilization. Abzymes generated by immunization with stable transition-state analogue designed to mimic high energy tetrahedral intermediate of ester hydrolysis such as phosphonate monoester w

Ref: Lerner et al Science 1991 252:659 catalytic antibodies abzyme; Shabat et al Transition state analog phosphonate ester.

Monoclonal antibodies are produced by:

Mammalian antibody-secreting plasma cells are terminally differentiated, possessing an extensively expanded endoplasmic reticulum and unfolded protein response activated to sustain immunoglobulin production at up to 10,000 molecules per second, but these cells quickly trigger p53 dependent apoptosis and survive only days in vitro. To overcome limited lifespan, Georges Kohler and Cesar Milstein in 1975 created hybridoma technology that couples specificity donor with immortal partner. Splenic B lymphocytes isolated from hyperimmunized mouse provide functional heavy and light chain loci after som

Ref: Kohler & Milstein Nature 1975 256:495 hybridoma; Alberts Molecular Biology of Cell 6th ed Chapter 8 monoclonal production.

Polyclonal antibodies differ from monoclonal antibodies because they:

Immunization with a complex protein or whole pathogen simultaneously displays many surface features that can be recognized by the adaptive immune system. Each epitope activates distinct naive B cells bearing complementary B cell receptors generated through VDJ recombination and junctional diversity, driving clonal expansion in germinal centers with help from follicular helper T cells. Differentiation produces plasma cells secreting antibodies with different paratopes, isotypes, and affinities that collectively coat the same antigen particle. The resulting serum therefore constitutes a heteroge

Ref: Kuby Immunology 8th ed Chapter 4 Antibody binding; Janeway Immunobiology NCBI Bookshelf NBK27130 polyclonal multi-epitope recognition.

Which of the following is an example of therapeutic monoclonal antibody?

Cetuximab chimeric IgG1 mAb 152 kDa murine variable regions grafted human constant domains preserving antigen binding specificity reducing HAMA response versus purely murine. Target EGFR HER1 encoded EGFR 7p11.2 overexpressed colorectal lung HNSCC via amplification autocrine loop. Physiologic ligands EGF TGF-alpha amphiregulin bind ECD III inducing conformational change exposing dimerization arm domain II allowing homo hetero-dimerization HER2 HER3 autophosphorylation tyrosines Tyr1068 Tyr1086 Tyr1173 recruiting adaptors Grb2 Shc activating KRAS GTP exchange GDP GTP triggering BRAF MEK ERK pro

Ref: FDA Erbitux Cetuximab EGFR MOA Label; NEJM Cetuximab Colorectal KRAS Wild-type 2008 Van Cutsem; Janeway EGFR Antibody Therapy ADCC Mechanism.

Monoclonal antibodies are produced by:

Monoclonal antibodies originate immortalized hybridoma lines fusing single antibody-secreting B lymphocyte with myeloma partner preserving exactly one immunoglobulin gene rearrangement producing uniform paratope. Protocol begins immunization BALB/c mice purified antigen HER2 extracellular domain mixed Freund's adjuvant stimulating germinal center spleen. Four days after final booster splenocytes enriched plasma blasts expressing high-affinity surface IgG harvested. Fusion mediated PEG 1500 or electrofusion aligning cells pearl chains creates heterokaryons containing nuclei both parents tetrapl

Ref: Kohler and Milstein Nature 1975 Hybridoma Monoclonal Generation; Janeway Hybridoma Technology Production Chapter 5; Lodish Antibody Production Hybridoma Cells Method.

Polyclonal antibodies differ from monoclonal antibodies because they:

Polyclonal antibody preparations heterogeneous mixture immunoglobulin molecules diverse B lymphocyte clones responding complex immunogen multiple antigenic determinants repetitive epitopes. Each naive B cell generates unique BCR random recombination RAG-mediated VDJ joining heavy chain variable diversity joining segments VJ joining light chain kappa lambda diversified junctional addition non-templated nucleotides TdT and somatic hypermutation germinal centers introducing point mutations rate 10^-3 per base division selecting higher affinity via follicular dendritic cell presentation. Immunizat

Ref: Janeway Immunobiology 9th ed Polyclonal vs Monoclonal Diversity Chap 5; NCBI Bookshelf Antibody Diversity Mechanism; Campbell Immunology Antibody Response Polyepitopic.