Binding of Immunoglobulin G to Protoporphyrin IX and Its Derivatives: Evidence the Fab Domain Recognizes the Protoporphyrin Ring

Immunoglobulin G (IgG) is known to bind zinc via the Fc domain. In this study, biotinylated protoporphyrin IX (PPIX) was incubated with human IgG and then zinc-immobilized Sepharose beads (Zn-beads) were added to the mixture. After washing the beads, the binding of biotinylated PPIX with IgG trapped on Zn-beads was detected using alkaline phosphatase (ALP)-labeled avidin. Human IgG and its Fab domain coated on microtiter plate wells recognized biotin-labeled PPIX and its derivatives, Fe-PPIX and Zn-PPIX, whereas the Fc domain showed some extent of reaction only with Zn-PPIX. When rabbit anti-bovine transferrin (Tf) antibodies were incubated with biotinylated PPIX, the binding of anti-Tf antibodies with apo-Tf was indirectly detected using ALP-labeled avidin, suggesting that even if the antibody is modified with PPIX, the antibody-antigen reaction occurs. These results suggest that the IgG Fab domain recognizes PPIX and its derivatives, probably via the recognition of the PPIX ring. It is unlikely that binding between the Fab domain and PPIX affects the Fc domain-zinc interaction or antigen-antibody reaction.

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Evaluation of a Sensor Detection Ability and Reactivity of Antigen-antibody Reaction on Surface of a Polymer Sheet

IEEJ Transactions on Sensors and Micromachines ◽

10.1541/ieejsmas.139.303 ◽

2019 ◽

Vol 139 (9) ◽

pp. 303-309

Author(s):

Takaaki Isoda ◽

Hiroki Ichihara ◽

Kodai Ryujin

Keyword(s):

Detection Ability ◽

Polymer Sheet ◽

Antibody Reaction ◽

Antigen Antibody ◽

Sensor Detection

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Pharmaceutical immunoglobulin G impairs anti-carcinoma activity of oxaliplatin in colon cancer cells

British Journal of Cancer ◽

10.1038/s41416-021-01272-6 ◽

2021 ◽

Author(s):

Yuru Shang ◽

Xianbin Zhang ◽

Lili Lu ◽

Ke Jiang ◽

Mathias Krohn ◽

...

Keyword(s):

Colon Cancer ◽

Cell Viability ◽

Cancer Patients ◽

Cell Lines ◽

Cancer Cell ◽

Immunoglobulin G ◽

Cancer Cell Lines ◽

Human Igg ◽

Western Blots ◽

Igg Receptors

Abstract Background Recent evidence proves that intravenous human immunoglobulin G (IgG) can impair cancer cell viability. However, no study evaluated whether IgG application benefits cancer patients receiving chemotherapeutics. Methods Influence of pharmaceutical-grade human IgG on the viability of a series of patient-derived colon cancer cell lines with and without chemotherapeutic intervention was determined. Cell death was analysed flow cytometrically. In addition, the influence of oxaliplatin and IgG on the ERK1/2-signalling pathway was evaluated by western blots. Results We evaluated the effects of pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, in combination with chemotherapeutics. We did not observe any significant effects of IgG on tumour cell viability directly; however, human IgG significantly impaired the anti-tumoral effects of oxaliplatin. Primary cancer cell lines express IgG receptors and accumulate human IgG intracellularly. Moreover, while oxaliplatin induced the activation of ERK1/2, the pharmaceutical IgG inhibited ERK1/2 activity. Conclusions The present study demonstrates that pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, can impair the anti-carcinoma activity of oxaliplatin. These data strongly suggest that therapeutic IgG as co-medication might have harmful side effects in cancer patients. The clinical significance of these preclinical observations absolutely advises further preclinical, as well as epidemiological and clinical research.

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Evaluation of Shear Horizontal Surface Acoustic Wave Biosensors Using “Layer Parameter” Obtained from Sensor Responses during Immunoreaction

Sensors ◽

10.3390/s21144924 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4924

Author(s):

Koji Kano ◽

Hiromi Yatsuda ◽

Jun Kondoh

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Horizontal Surface ◽

Propagation Characteristics ◽

Viscosity Change ◽

Layer Parameter ◽

Antibody Reaction ◽

Antigen Antibody ◽

Shear Horizontal ◽

Molecular Dimensions

Shear horizontal surface acoustic wave (SH-SAW) biosensors measure the reaction of capture antibodies immobilized on the sensing surface to capture test molecules (antigens) by using the change in SH-SAW propagation characteristics. SH-SAW displacement exists not only on the SH-SAW propagating surface, but also partially penetrates the specimen liquid to a certain depth, which is determined by the liquid properties of the specimen and the operating frequency of the SH-SAW. This phenomenon is called viscosity penetration. In previous studies, the effect of viscosity penetration was not considered in the measurement of SH-SAW biosensors, and the mass or viscosity change caused by the specific binding of capture antibodies to the target antigen was mainly used for the measurement. However, by considering the effect of viscosity penetration, it was found that the antigen–antibody reaction could be measured and the detection characteristics of the biosensor could be improved. Therefore, this study aims to evaluate the detection properties of SH-SAW biosensors in the surface height direction by investigating the relationship between molecular dimensions and SH-SAW propagation characteristics, which are pseudo-changed by varying the diameter of gold nanoparticles. For the evaluation, we introduced a layer parameter defined by the ratio of the SH-SAW amplitude change to the SH-SAW velocity change caused by the antigen–antibody reaction. We found a correlation between the layer parameter and pseudo-varied molecular dimensions. The results suggest that SH-SAW does not only measure the mass and viscosity but can also measure the size of the molecule to be detected. This shows that SH-SAW biosensors can be used for advanced functionality.

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