Antibody

In two previously described donors, the extracellular domain of LAIR1, a collagen-binding inhibitory receptor encoded on chromosome 19 (ref. 1), was inserted between the V and DJ segments of an antibody. This insertion generated, through somatic mutations, broadly reactive antibodies against RIFINs, a type of variant antigen expressed on the surface of Plasmodium falciparum-infected erythrocytes. To investigate how frequently such antibodies are produced in response to malaria infection, we screened plasma from two large cohorts of individuals living in malaria-endemic regions. Here we report that 5-10% of malaria-exposed individuals, but none of the European blood donors tested, have high levels of LAIR1-containing antibodies that dominate the response to infected erythrocytes without conferring enhanced protection against febrile malaria. By analysing the antibody-producing B cell clones at the protein, cDNA and gDNA levels, we characterized additional LAIR1 insertions between the...

Viral entry targets with therapeutic neutralizing potential are subject to multiple escape mechanisms, including antigenic drift, immune dominance of functionally irrelevant epitopes, and subtle variations in host cell mechanisms. A surprising finding of recent years is that potent neutralizing antibodies to viral epitopes independent of strain exist, but are poorly represented across the diverse human population. Identifying these antibodies and understanding the biology mediating the specific immune response is thus difficult. An effective strategy for meeting this challenge is to incorporate multiplexed antigen screening into a high throughput survey of the memory B cell repertoire from immune individuals. We used this approach to discover suites of cross-clade antibodies directed to conformational epitopes in the stalk region of the influenza A hemagglutinin (HA) protein and to select high-affinity anti-peptide antibodies to the glycoprotein B (gB) of human cytomegalovirus. In e...

A pesar de que las nuevas terapias inmunosupresoras han mejorado notablemente la evolucion clinica de los trasplantes renales, los rechazos agudo y cronico siguen limitando la sobrevida a largo plazo del injerto. En base a lo anterior, el objetivo de este estudio fue determinar la presencia de anticuerpos sericos contra antigenos de histocompatibilidad (HLA) clase I y clase II en ninos con rechazo agudo del injerto renal. Metodos. Se realizo un estudio clinico prospectivo en pacientes con trasplante renal que presentaron rechazo agudo del injerto. Se les tomo muestra de suero al momento de la biopsia renal, misma que fue utilizada para la deteccion de anticuerpos contra antigenos HLA de clase I y II por ensayo basado en equipo fuoroanalizador (Luminex) y microperlas cubiertas con antigenos clase I y clase II de One Lambda. Resultados. De 21 pacientes estudiados, 17 pacientes (81%), fueron diagnosticados con rechazo celular y cuatro (19%) con rechazo agudo mediado por anticuerpos. El...

Elevated renal uptake and prolonged retention of radiolabeled antibody fragments and peptides is a problem in the therapeutic application of such agents. Over recent years, one of the focuses of research has therefore been to develop suitable methods to reduce this renal uptake, and to evaluate whether the resulting methodology will benefit therapy with antibody fragments and peptides. In these studies it has been shown that the kidney uptake of antibody fragments in animals can be reduced in a dose-dependent manner by almost one order of magnitude by the systemic administration of cationic amino acids and their derivatives, whereas the uptake in all other organs, as well as the tumor, remains unaffected. A similar reduction in renal retention is achieved for all intracellularly retained radionuclides (e.g., radiometals) or radioiodinated immunoconjugates, as well as for smaller peptides. Lysine is usually the preferred agent, and its d- and l-isomers are equally effective whether given intraperitoneally or orally. Amino sugars are effective, but their N-acetyl derivatives, lacking the positive charge, are not. Basic polypeptides are also effective, and their potency increases with increasing molecular weight (i.e., the amount of positive charges per molecule). Urine analysis of treated individuals shows the excretion of unmetabolized, intact fragments or peptides, in contrast to mostly low-molecular-weight metabolites in untreated controls. In therapy studies using radiometal-conjugated Fab fragments, the kidney is the first dose-limiting organ. Administration of cationic amino acids results in a substantial increase in the maximum tolerated dose of such Fab fragments. No biochemical or histological evidence of renal damage has been observed under these conditions. As was the case in animal studies, in pilot clinical trials the renal uptake in patients injected with Fab′ fragments and given amino acids could be decreased significantly, whereas the uptake by all other organs remained unaffected. These recent studies indicate that a variety of basic compounds are capable of inhibiting the tubular reabsorption of peptides and proteins, thus significantly lowering the renal uptake of antibody fragments or peptides in both animals and patients. On a molecular basis, the effect seems to rely essentially on the presence of a positively charged amino group. Thus, radiation nephrotoxicity of antibody fragments and peptides can be overcome successfully; this may provide new prospects for cancer therapy with radiolabeled antibody fragments and peptides.

Virus-induced autoimmunity may play a causal role in autism. To examine the etiologic link of viruses in this brain disorder, we conducted a serologic study of measles virus, mumps virus, and rubella virus. Viral antibodies were measured by enzyme-linked immunosorbent assay in the serum of autistic children, normal children, and siblings of autistic children. The level of measles antibody, but not mumps or rubella antibodies, was significantly higher in autistic children as compared with normal children (P = 0.003) or siblings of autistic children (P ≤ 0.0001). Furthermore, immunoblotting of measles vaccine virus revealed that the antibody was directed against a protein of approximately 74 kd molecular weight. The antibody to this antigen was found in 83% of autistic children but not in normal children or siblings of autistic children. Thus autistic children have a hyperimmune response to measles virus, which in the absence of a wild type of measles infection might be a sign of an abnormal immune reaction to the vaccine strain or virus reactivation.

One major challenge in nanomedicine is the selective delivery of nanoparticles to diseased tissues. Nanoparticle delivery systems require targeting for specific delivery to pathogenic sites when enhanced permeability and retention (EPR) is not suitable or inefficient. Nanoparticle functionalization is a widely-used technique for targeting ligand conjugation; these ligands possess inherent abilities to direct nanoparticle selective binding. This review illustrates methods of ligand-nanoparticle functionalization, provides a cross-section of various ligand classes, including small molecules, peptides, antibodies, engineered proteins, or nucleic acid aptamers, and discusses some unconventional approaches currently under investigation.

Background: Cigarette smoking has been linked with the suppression of immune responses and increased susceptibility to numerous infections in humans. Tetanus is also a major public health problem in many countries. The aim of the present study was to evaluate the serum levels of anti-tetanus toxin antibodies in c igarette smoking and healthy non-smoking people .

  Materials and Methods: A total of 100 c igarette smokers and 100 age-matched healthy non-smoker individuals were enrolled in this descriptive study. A blood sample was collected from each participant. The samples were tested for the levels of anti-tetanus toxin antibodies b y use of enzyme linked immunosorbent assay.

  Results: The seroprotective rate of anti-tetanus toxin antibodies in non-smoking group (99%) was significantly higher than that observed in c igarette smoking group (78%, P<0.0001). The mean titer of anti-tetanus toxin antibodies in non-smoking group ( 5.32± 0.26 IU/ml) was also significantly higher than that in smoker subjects ( 1.03 ± 0.16 IU/ml P<0.0001). The mean titer of anti-tetanus toxin antibodies in individuals with smoking duration >10 years was significantly lower than that among smokers with smoking duration ≤10 years (0.59 ± 0.12 IU/ml vs 1.98 ± 0.41 IU/ml P<0.001). The seroprotection rate was also significantly lower in persons with smoking duration >10 years in comparison to smokers with smoking duration ≤10 years (72.1% vs 90.6% P=0.037). The mean titer of anti-tetanus toxin antibodies in individuals with daily smoking >10 cigarettes was also significantly lower in comparison to smokers with daily smoking ≤10 cigarettes (0.68 ± 0.15 IU/ml vs 1.63 ± 0.36 IU/ml P<0.001).

  Conclusion: These results showed lower levels of anti-tetanus toxin antibodies in cigarette smokers which represents c igarette smoking as a risk factor for susceptibility to tetanus. A negative association was also observed between the immunity to tetanus and smoking burden.

O uso dos hemocomponentes do grupo
sangüíneo “O” em transfusões não isogrupos,
pode acarretar reações transfusionais, caso as
aglutininas anti-A, anti-B e anti-AB,
presentes no soro/plasma do doador
apresentarem títulos elevados (1/100). As
reações transfusionais mais relatadas com
anticorpos de altos títulos são ocasionadas
por concentrado de plaquetas, devido à
presença de plasma nesse hemocomponente.
Tendo em vista, a pequena quantidade de
estudos sobre a freqüência das aglutininas
anti-A, anti-B e anti-AB, e considerando sua
importância nas transfusões, o objetivo deste
trabalho foi avaliar a freqüência dos títulos
dessas aglutininas em 564 amostras de soro
sangue do grupo sangüíneo "O" do
Hemonúcleo de Guarapuava mostrou que
317 (56,2%) doações foram realizadas por
indivíduos do sexo masculino na faixa etária
de 18 a 45 anos de idade. A partir dos dados
de freqüências elevadas das aglutininas A, B
e AB no Hemonúcleo de Guarapuava, podese
sugerir que é de grande importância a
pesquisa dos títulos dessas aglutininas na
rotina de bancos de sangue e que há
necessidade da implantação de protocolos
transfusionais específicos que padronize a
pesquisa desses anticorpos de altos títulos e
torne a prática transfusional ainda mais
segura

Microfluidic devices are increasingly important in biomedical assays. In this paper, we review recent progress on these devices for chemical amplification, hybridization, separation, and detection of nucleic acids. Recent developments in microfluidic technologies for detection of protein binding events in immunoassay applications are also reviewed.

Enzyme-cleaved antibodies are used widely for the treatment of envenoming. Such products should comprise only ‘highly pure’ immunoglobulin fragments since Fc or other contaminating protein fragments or their aggregates may lead to side effects. The digestion of ovine antiserum and its purified IgG were investigated using pepsin and trypsin. Trypsin was effective at digesting purified IgG but unsuitable for the direct digestion of serum. In contrast, pepsin was highly effective at digesting all unwanted serum components to low molecular weight (≤13 kDa) fragments while leaving the ~100-kDa F(ab′)2 intact. The optimum pH for pepsin digestion was between 3.25 and 3.50. The effects of salt concentration and pH on the digestion products were investigated by size exclusion chromatography under various conditions, which revealed a pH-dependent aggregation of some of the low molecular weight Fc and non-IgG fragments. These high molecular weight aggregates were not shown by SDS-PAGE. Unwanted low molecular weight fragments could be removed simply by diafiltration with a 30-kDa nominal molecular weight cutoff membrane and piperazine buffer (containing 150 mM NaCl, pH 6), leaving an F(ab′)2 solution contaminated only with some pepsin and a small amount of the aggregated low molecular weight fragments. These highly acidic contaminants were then removed easily using an anion exchange column and the F(ab′)2 produced following a subsequent concentration step was essentially free from pepsin and aggregates with a purity of over 96% and a yield of 19.3 g F(ab′)2/l serum. This novel, high yield method for processing serum to highly pure F(ab′)2 avoids salt precipitation and centrifugation and should be suitable for large-scale production.

Understanding the nature of neutralization may provide information for crafting improvements in HIV vaccines. Using JR-FL as a prototype primary pseudovirus, we first investigated anti-HIV monoclonal antibodies (mAbs) in several neutralization formats designed to elucidate the timing of neutralization. MAb b12 was most effective before receptor binding, 2G12 neutralized effectively even after CD4 binding, and X5 and a V3 loop mAb (LE311) were inactive in a standard format but were induced by sCD4. Consistent with this latter finding, native PAGE indicated that X5 and V3 mAb binding to Envelope trimers was dependent on sCD4 binding. In contrast, 2F5 and 4E10 were active even post-CD4/CCR5 engagement. We next analyzed the neutralization mechanism of a panel of HIV+ donor plasmas of various potencies. All mediated high levels of post-CD4 neutralization that was not associated with activity in the standard format. None, however, neutralized effectively in the post-CD4/CCR5 format, sugge...

Recent advances in HIV vaccine development include initiation of the first efficacy trials and substantial expansion of the preclinical pipeline. Several preclinical candidate vaccines have induced strong cellular immune responses and provided impressive protection against AIDS in non-human primate models; however, candidates that induce broadly neutralizing antibodies remain elusive.