Biophysical mechanism of the scavenger site near T cell-presented epitopes

Lü, Shan; Reyes, Victor E.; Bositis, Christopher M.; Goldschmidt, Thomas G.; Lam, Valery; Torgerson, Rochelle R.; Ciardelli, Thomas L.; Hardy, Larry W.; Lew, Robert A.; Humphreys, Robert E.

doi:10.1016/0264-410x(92)90410-l

Cited by 8 publications

(2 citation statements)

References 32 publications

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“…When the sample of Hb-c-particles was half diluted and subjected to CD study, the obtained spectrum also crossed over the same point (Figure 5A). So the percentage helicity of Hb in the particles could be assessed by comparing the ellipticity at 222 nm 45 . As the minimum at 222 nm for Hb-c-particles only shows minor different from that of free Hb, we can conclude that the percentage helicity of Hb conjugated to particles was close to native Hb, indicating negligible change in the secondary structure of Hb-c-particles.…”

Section: Resultsmentioning

confidence: 99%

Low Modulus Biomimetic Microgel Particles with High Loading of Hemoglobin

Chen¹,

Merkel²,

Pandya³

et al. 2012

Biomacromolecules

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We synthesized extremely deformable red blood cell-like microgel particles and loaded them with bovine hemoglobin (Hb) to potentiate oxygen transport. With similar shape and size as red blood cells (RBCs), the particles were fabricated using the PRINT® (Particle Replication In Non-wetting Templates) technique. Low crosslinking of the hydrogel resulted in very low mesh density for these particles, allowing passive diffusion of hemoglobin throughout the particles. Hb was secured in the particles through covalent conjugation of the lysine groups of Hb to carboxyl groups in the particles via EDC/NHS coupling. Confocal microscopy of particles bound to fluorescent dye-labeled Hb confirmed the uniform distribution of Hb throughout the particle interior, as opposed to the surface conjugation only. High loading ratios, up to 5 times the amount of Hb to polymer by weight, were obtained, without a significant effect on particle stability, shape, though particle diameter decreased slightly with Hb conjugation. Analysis of the protein by circular dichroism (CD) spectroscopy showed that the secondary structure of Hb was unperturbed by conjugation to the particles. Methemoglobin in the particles could be maintained at a low level and the loaded Hb could still bind oxygen as studied by UV-vis spectroscopy. Hb-loaded particles with moderate loading ratios demonstrated excellent deformability in microfluidic devices, easily deforming to pass through restricted pores half as wide as the diameter of the particles. The suspension of concentrated particles with Hb concentration of 5.2 g/dL showed comparable viscosity to that of mouse blood, and the particles remained intact even after being sheared at a constant high rate (1,000 1/s) for 10 min. Armed with the ability to control size, shape, deformability, and loading of Hb into RBC mimics, we will discuss the implications for artificial blood.

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Section: Resultsmentioning

confidence: 99%

Low Modulus Biomimetic Microgel Particles with High Loading of Hemoglobin

Chen¹,

Merkel²,

Pandya³

et al. 2012

Biomacromolecules

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“…32]. This strip is hypothesized to regulate scavenging of the sequence presented to T cells [33][34][35] by promoting adsorption to the wall of an endosomal vesicle as a helix (Fig, 3), Such adsorbed. amphipathic helices may be relatively resistant to further proteolysis.…”

Section: Identification Of Helper and Suppressor Epitopes In Fviiimentioning

confidence: 99%

Hypothesis for the Control of Clotting Factor VIII Inhibitory Antibodies by Decreasing Potency of Helper T‐Cell‐Recognized Epitopes in Factor VIII

Tiarks¹,

Humphreys²,

Anderson

et al. 1992

Scand J Immunol

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The study of the immunobiology of FVIII inhibitors may lead to new therapies for this potentially severe complication of haemophilia A and to new principles for the use of therapeutic proteins. In order to characterize the idiotype-anti-idiotype networks regulating FVIII inhibitors, we developed rabbit anti-idiotypic sera to 7 murine inhibitors and found at least 12 independent FVIII loci to which inhibitors could be raised. Rabbit antisera to the FVIII peptide, Ser1687-Thr1695, characterized one functional site to which about 46% of patients' inhibitor sera reacted. The multiplicity of inhibitor-recognized epitopes in FVIII makes it impractical, at the present time, to develop clinically useful specific anti-idiotypic therapies for FVIII inhibitors. Alternatively, one might induce genomic mutations in recombinant FVIII molecules to decrease immunogenicity of epitopes recognized by T helper cells. Methods to design such altered therapeutic proteins are presented, based on changing the longitudinal hydrophobic strip-of-helix which is in or near many T-cell-presented epitopes.

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