Antibodies: a Paradigm for the Evolution of Molecular Recognition

2002 ◽  
Vol 30 (4) ◽  
pp. 341-350 ◽  
Author(s):  
M. S. Neuberger
Keyword(s):  
Affinity Maturation ◽  
The Body ◽  
Immunoglobulin Genes ◽  
Binding Characteristics ◽  
Humoral Immune ◽  
High Affinity ◽  
Selection Processes ◽  
Specific Affinity ◽  
Mutation And Selection

Novel proteins have been elaborated over evolutionary time by an iterative alternation of mutation and selection. In a similar way, the humoral immune system also uses an iterative alternation of mutation and selection to generate novel antibodies that display a high affinity for their cognate antigen - but this is achieved in a matter of a days. Gene rearrangement is used to produce a primary repertoire of antibodies and, on entering the body, antigen triggers the clonal expansion of those B lymphocytes that express a cognate antibody, albeit one of low affinity. Rapid and specific affinity maturation is then achieved by subjecting the immunoglobulin genes in the rapidly expanding B cells to a period of intense mutation. The intensity of this mutational assault is tolerated because it is targeted specifically to the immunoglobulin genes, causing relatively little damage to other loci. Antigen-mediated selection then allows the preferential expansion of those mutants expressing antibodies displaying improved binding characteristics. Here, studies are described that have been performed to glean insight into the mechanisms of the hypermutation and selection processes. Experiments are also described in which an attempt has been made to recapitulate aspects of physiological antibody generation in vitro, allowing the development of novel approaches to the generation of proteins with high-affinity binding sites.

scholarly journals High affinity germinal center B cells are actively selected into the plasma cell compartment

2006 ◽  
Vol 203 (11) ◽  
pp. 2419-2424 ◽  
Author(s):  
Tri Giang Phan ◽  
Didrik Paus ◽  
Tyani D. Chan ◽  
Marian L. Turner ◽  
Stephen L. Nutt ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
Plasma Cell ◽  
Plasma Cells ◽  
Affinity Maturation ◽  
The Body ◽  
Plasma Cell Differentiation ◽  
High Affinity

A hallmark of T cell–dependent immune responses is the progressive increase in the ability of serum antibodies to bind antigen and provide immune protection. Affinity maturation of the antibody response is thought to be connected with the preferential survival of germinal centre (GC) B cells that have acquired increased affinity for antigen via somatic hypermutation of their immunoglobulin genes. However, the mechanisms that drive affinity maturation remain obscure because of the difficulty in tracking the affinity-based selection of GC B cells and their differentiation into plasma cells. We describe a powerful new model that allows these processes to be followed as they occur in vivo. In contrast to evidence from in vitro systems, responding GC B cells do not undergo plasma cell differentiation stochastically. Rather, only GC B cells that have acquired high affinity for the immunizing antigen form plasma cells. Affinity maturation is therefore driven by a tightly controlled mechanism that ensures only antibodies with the greatest possibility of neutralizing foreign antigen are produced. Because the body can sustain only limited numbers of plasma cells, this “quality control” over plasma cell differentiation is likely critical for establishing effective humoral immunity.

Shark Attack: High affinity binding proteins derived from shark vNAR domains by stepwise in vitro affinity maturation

2014 ◽  
Vol 191 ◽  
pp. 236-245 ◽  
Author(s):  
Stefan Zielonka ◽  
Niklas Weber ◽  
Stefan Becker ◽  
Achim Doerner ◽  
Andreas Christmann ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Affinity Maturation ◽  
Affinity Binding ◽  
High Affinity Binding ◽  
High Affinity

Pharmacological profile of antihistamines: focus on unwanted drug interactions

2021 ◽  
Vol 17 (4) ◽  
pp. 46-56
Author(s):  
Alexander S. Dukhanin
Keyword(s):  
Drug Interactions ◽  
Second Generation ◽  
The Body ◽  
Pharmacological Profile ◽  
Luminal Membrane ◽  
Pharmacokinetic Properties ◽  
System 2 ◽  
Specific Affinity ◽  
Histamine H1 Receptors

Differences between individual antihistamines are determined by such pharmacokinetic properties as the rate and completeness of absorption, half-life, the participation of hepatic and renal mechanisms of elimination from the body. Pharmacodynamic features of the antihistamine include selectivity and affinity for histamine H1-receptors and the presence of central effects. The mechanisms of the development of unwanted drug interactions with second-generation antihistamines are analyzed in detail. Three levels of interaction have been identified: 1) hepatic enzymes of the P450 system; 2) membrane carriers of organic anions (OATP) transport proteins on the sinusoidal membrane of hepatocytes and the luminal membrane of the epithelium of the proximal nephron tubule; 3) P-glycoprotein (Pgp, ABCB1-protein) of epithelial cells of the small intestine the area of absorption of oral forms of antihistamines, the epithelium of the proximal tubule and the BBB (blood-brain barrier). The emphasis is made on the description of the dependence of the pharmacological profile of antihistamines on its chemical structure. The elasticity of the bilastine molecule, the ability to induce a change in conformation underlies the high complementarity of bilastine to the recognition site of the H1-receptor which is a high affinity. Experimental evaluation confirms this conclusion: the dissociation constant (Dс) of the bilastin-receptor complex is in the nM concentration range. The bilastine molecule, as a representative of antihistamines with zwitterionic properties, carries both a positive and a negative charge at a physiological pH, making it difficult for its penetration into the brain. The peculiarities of the chemical nature of the bilastine molecule are reflected in the specific pharmacological profile of AGP. In vitro studies have shown a high specific affinity of bilastine for H1-receptors with a very low affinity for other histamine receptors (H2, H3, H4), serotonin, bradykinin, muscarinic and adrenergic receptors). According to this indicator, bilastine is 3 times higher than cetirizine and 5 times higher than fexofenadine. Bilastine is practically not metabolized in the body and is excreted mainly unchanged, and also does not have a cardiotoxic effect. Bilastine is well tolerated; as a therapeutic dose it has a less pronounced sedative potential compared to other second-generation antihistamines.

scholarly journals Rapid Affinity Maturation of Novel Anti-PD-L1 Antibodies by a Fast Drop of the Antigen Concentration and FACS Selection of Yeast Libraries

2019 ◽  
Vol 2019 ◽  
pp. 1-22 ◽  
Author(s):  
Biancamaria Cembrola ◽  
Valentino Ruzza ◽  
Fulvia Troise ◽  
Maria Luisa Esposito ◽  
Emanuele Sasso ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Surface Display ◽  
Affinity Maturation ◽  
Yeast Surface Display ◽  
Antigen Concentration ◽  
Selection Scheme ◽  
High Affinity ◽  
Novel Approach ◽  
Yeast Surface

The affinity engineering is a key step to increase the efficacy of therapeutic monoclonal antibodies and yeast surface display is the most widely used and powerful affinity maturation approach, achieving picomolar binding affinities. In this study, we provide an optimization of the yeast surface display methodology, applied to the generation of potentially therapeutic high affinity antibodies targeting the immune checkpoint PD-L1. In this approach, we coupled a 10-cycle error-prone mutagenesis of heavy chain complementarity determining region 3 of an anti‐PD-L1 scFv, previously identified by phage display, with high-throughput sequencing, to generate scFv-yeast libraries with high mutant frequency and diversity. In addition, we set up a novel, faster and effective selection scheme by fluorescence-activated cell sorting, based on a fast drop of the antigen concentration between the first and the last selection cycles, unlike the gradual decrease typical of current selection protocols. In this way we isolated 6 enriched mutated scFv-yeast clones overall, showing an affinity improvement for soluble PD-L1 protein compared to the parental scFv. As a proof of the potency of the novel approach, we confirmed that the antibodies converted from all the mutated scFvs retained the affinity improvement. Remarkably, the best PD-L1 binder among them also bound with a higher affinity to PD-L1 expressed in its native conformation on human-activated lymphocytes, and it was able to stimulate lymphocyte proliferation in vitro more efficiently than its parental antibody. This optimized technology, besides the identification of a new potential checkpoint inhibitor, provides a tool for the quick isolation of high affinity binders.

scholarly journals ON THE NATURE OF BACTEREMIA IN EXPERIMENTAL PNEUMOCOCCAL PNEUMONIA IN THE DOG

1953 ◽  
Vol 97 (2) ◽  
pp. 297-314 ◽  
Author(s):  
Lucien A. Gregg ◽  
O. H. Robertson
Keyword(s):  
Pneumococcal Pneumonia ◽  
The Body ◽  
Bactericidal Action ◽  
Principal Mechanism ◽  
Shed Blood ◽  
Humoral Immune ◽  
Large Numbers ◽  
Experimental Canine

With the purpose of ascertaining the influence exerted by the pneumococcidal activity of the blood on the course of bacteremia occurring in experimental canine pneumococcal pneumonia, a study was made of the rates at which intravenously injected pneumococci disappeared from the circulation and the shed blood of diseased dogs. Preliminary studies on normal animals showed that blood containing hundreds of thousands of pneumococci per cc. immediately after injection usually became sterile or nearly so within an hour's time. Simultaneous observations carried out on the blood in vitro showed an analogous rapid disappearance of the microorganisms, although the effect was not quite as marked. Similar tests on non-bacteremic dogs with pneumonia revealed essentially the same ability of the body to dispose of large numbers of circulating pneumococci. The shed blood likewise exhibited marked bactericidal power. The occurrence of bacteremia during pneumonia did not retard greatly the rate at which injected pneumococci disappeared from the circulation, as compared with the non-bacteremic state. After several hours the numbers of circulating microorganisms were approximately the same as prior to the intravenous injection. Blood in vitro often cleared as fully as it did in vivo over the same length of time. Studies on the role played by humoral immune substances in the bactericidal action of the blood showed that while their presence was necessary for maximum killing power, and that bacteremic blood lacking humoral immune properties was rarely capable of self-sterilization in vitro, nevertheless such blood often retained considerable bactericidal potency as shown by its ability to reduce materially the numbers of pneumococci added to it. This phenomenon is discussed. The marked pneumococcidal capacity of the blood exhibited by dogs with experimental pneumococcal pneumonia and its persistence during bacteremia suggest that this constitutes the principal mechanism for limiting the degree of blood invasion. The similarity of the findings in canine and human pneumococcal lobar pneumonia is pointed out.

scholarly journals A new class of errant DNA polymerases provides candidates for somatic hypermutation

2001 ◽  
Vol 356 (1405) ◽  
pp. 47-51 ◽  
Author(s):  
Brigette Tippin ◽  
Myron F. Goodman
Keyword(s):  
Somatic Hypermutation ◽  
Dna Polymerases ◽  
Variable Region ◽  
Affinity Maturation ◽  
Immunoglobulin Genes ◽  
New Class ◽  
Eukaryotic Dna ◽  
Factor Governing

The mechanism of somatic hypermutation of the immunoglobulin genes remains a mystery after nearly 30 years of intensive research in the field. While many clues to the process have been discovered in terms of the genetic elements required in the immunoglobulin genes, the key enzymatic players that mediate the introduction of mutations into the variable region are unknown. The recent wave of newly discovered eukaryotic DNA polymerases have given a fresh supply of potential candidates and a renewed vigour in the search for the elusive mutator factor governing affinity maturation. In this paper, we discuss the relevant genetic and biochemical evidence known to date regarding both somatic hypermutation and the new DNA polymerases and address how the two fields can be brought together to identify the strongest candidates for further study. In particular we discuss evidence for the in vitro biochemical misincorporation properties of human Rad30B/Pol ι and how it compares to the in vivo somatic hypermutation spectra.

Developmental bifurcation of human T follicular regulatory cells

2021 ◽  
Vol 6 (59) ◽  
pp. eabd8411
Author(s):  
Saumya Kumar ◽  
Válter R. Fonseca ◽  
Filipa Ribeiro ◽  
Afonso P. Basto ◽  
Ana Água-Doce ◽  
...  
Keyword(s):  
Affinity Maturation ◽  
In Vitro Assays ◽  
Lymphoid Tissues ◽  
Regulatory Cells ◽  
Healthy Human ◽  
High Affinity ◽  
Dynamic Relationship ◽  
Follicular Helper

Germinal centers (GCs) are anatomic structures where B cells undergo affinity maturation, leading to production of high-affinity antibodies. The balance between T follicular helper (TFH) and regulatory (TFR) cells is critical for adequate control of GC responses. The study of human TFH and TFR cell development has been hampered because of the lack of in vitro assays reproducing in vivo biology, along with difficult access to healthy human lymphoid tissues. We used a single-cell transcriptomics approach to study the maturation of TFH and TFR cells isolated from human blood, iliac lymph nodes (LNs), and tonsils. As independent tissues have distinct proportions of follicular T cells in different maturation states, we leveraged the heterogeneity to reconstruct the maturation trajectory for human TFH and TFR cells. We found that the dominant maturation of TFR cells follows a bifurcated trajectory from precursor Treg cells, with one arm of the bifurcation leading to blood TFR cells and the other leading to the most mature GC TFR cells. Overall, our data provide a comprehensive resource for the transcriptomics of different follicular T cell populations and their dynamic relationship across different tissues.

scholarly journals BH3-only protein Noxa regulates apoptosis in activated B cells and controls high-affinity antibody formation

Blood ◽  
2012 ◽  
Vol 119 (6) ◽  
pp. 1440-1449 ◽  
Author(s):  
Felix M. Wensveen ◽  
Ingrid A. M. Derks ◽  
Klaas P. J. M. van Gisbergen ◽  
Alex M. de Bruin ◽  
Joost C. M. Meijers ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Influenza Infection ◽  
Affinity Maturation ◽  
Antibody Responses ◽  
Booster Immunization ◽  
High Affinity ◽  
Activated B Cells

Abstract The efficiency of humoral immune responses depends on the selective outgrowth of B cells and plasmacells that produce high affinity antibodies. The factors responsible for affinity maturation of B cell clones in the germinal center (GC) have been well established but selection mechanisms that allow clones to enter the GC are largely unknown. Here we identify apoptosis, regulated by the proapoptotic BH3-only member Noxa (Pmaip1), as a critical factor for the selection of high-affinity clones during B cell expansion after antigen triggering. Noxa is induced in activated B cells, and its ablation provides a survival advantage both in vitro and in vivo. After immunization or influenza infection, Noxa−/− mice display enlarged GCs, in which B cells with reduced antigen affinity accumulate. As a consequence, Noxa−/− mice mount low affinity antibody responses compared with wild-type animals. Importantly, the low affinity responses correlate with increased immunoglobulin diversity, and cannot be corrected by booster immunization. Thus, normal elimination of low affinity cells favors outgrowth of the remaining high-affinity clones, and this is mandatory for the generation of proper antibody responses. Manipulation of this process may alter the breadth of antibody responses after immunization.

scholarly journals ON THE NATURE OF BACTEREMIA IN EXPERIMENTAL PNEUMOCOCCAL PNEUMONIA IN THE DOG

1953 ◽  
Vol 97 (2) ◽  
pp. 283-296 ◽  
Author(s):  
O. H. Robertson ◽  
Morton Hamburger ◽  
Lucien A. Gregg
Keyword(s):  
Humoral Immunity ◽  
Pneumococcal Pneumonia ◽  
The Body ◽  
Disease Course ◽  
Ample Evidence ◽  
Humoral Immune ◽  
Large Numbers ◽  
Relationship Of ◽  
The Relationship

In a study of the relationship of natural antipneumococcal immune substances to the incidence and course of bacteremia in dogs with experimental pneumococcus pneumonia the following findings came to light: (1) In non-bacteremic animals, natural immune substances, as measured by the pneumococcidal-promoting action of the serum, continue to be present in relatively undiminished concentration throughout the course of the infection. (2) With the advent of bacteremia these immune properties of the blood tend to decrease or disappear, depending on the degree of bacteremia and the length of the disease course, but in certain instances they persist despite the presence of large numbers of circulating pneumococci. (3) Disappearance of natural immune substances from the blood during bacteremia is followed by their reappearance upon cessation of the bacteremia. (4) Bacteremic blood containing antipneumococcal immune substances and a sufficient quantity of leucocytes is capable of destroying in vitro relatively large numbers of pneumococci and will often sterilize itself. (5) The sequence of bacteremia first, then diminution and disappearance of humoral immunity excludes this antipneumococcal action of the blood as being the principal inhibitor of blood invasion. These observations have been interpreted as indicating that the bacteremic state consists of a constant escape of pneumococci from the pulmonary lesion and an attempt on the part of the body to compensate for the depletion of circulating immune substances resulting from their progressive immobilization by the pneumococci and their products. Thus, the loss or retention of humoral immune substances in the presence of bacteremia would appear to depend on the rate at which the body can provide new supplies of antibodies and on the number of pneumococci being discharged into the circulation. While the pneumococcidal action of the blood may not be sufficient to prevent the occurrence of bacteremia our study provides ample evidence that it exerts a potent restraining effect on the increase in numbers of pneumococci in the circulation.

Sign in / Sign up

Export Citation Format

Share Document