Kim S, Shukla RK, Yu H, Baek A, Cressman SG, Golconda S, Lee GE, Choi H, Reneau JC, Wang Z, Huang CA, Liyanage NPM, Kim S (2022) CD3e-immunotoxin spares CD62Llo Tregs and reshapes organ-specific T-cell composition by preferentially depleting CD3ehi T cells. Front Immunol 13:1011190. doi: 10.3389/fimmu.2022.1011190
Objective: To use a new murine testing model to demonstrate a substantial enrichment of tissue-resident Foxp3+ Tregs following CD3e-IT treatment.
Summary: The multi-organ pharmacodynamics of CD3e-IT and potential treatment resistance mechanisms identified in this study may generate new opportunities to further improve this promising treatment.
Usage: Male C57BL/6J mice were injected into retro-orbital sinus with 15 μg S-CD3e-IT (Biotinylated Anti-CD3 mixed with Streptavidin-ZAP in sterile 200 μl PBS twice a day for four consecutive days.
Q: When using any of your Fab-Zap product line, the recommended final concentration is 4.5 nM. Is this based on experiments you have done? I question if at 4.5 nM my primary antibody will be saturated with Fab-ZAP secondary conjugate?
A: Yes, the 4.5 nM concentration is what we use to quality-control test our Fab-ZAP conjugates and why we recommend it in the literature. We also recommend only titrating your primary antibody. The 4.5 nM of Fab-ZAP should be enough to saturate your primary antibody. If you have a test of ~10 nM of primary antibody and you experience less cell death than ~1 nM, this will indicate “antibody competition” (i.e., your primary antibody is not saturated). The data sheet shows a cytotox with a nice example of this. (Fab-ZAP data sheet)
Goodyer WR, Beyersdorf BM, Duan L, van den Berg NS, Mantri S, Galdos FX, Puluca N, Buikema JW, Lee S, Salmi D, Robinson ER, Rogalla S, Cogan DP, Khosla C, Rosenthal EL, Wu SM (2022) In vivo visualization and molecular targeting of the cardiac conduction system. J Clin Invest e156955. doi: 10.1172/jci156955
Objective: To engineer targeted antibody conjugates directed against the cardiac conduction system (CCS) to allow visualization of the CCS in vivo.
Summary: Accidental injury to the CCS, a specialized set of cells embedded within the heart and indistinguishable from the surrounding heart muscle tissue, is a major complication in cardiac surgeries. They generated a fully human monoclonal Fab (hCNTN2) that targets the CCS with high specificity.
Usage: Streptavidin-ZAP was reacted with biotinylated hCNTN2 Fab to create hCNTN2-SAP. 100 ug of either hCNTN2-SAP and control-SAP were injected into wild-type mice with a single tail-vein injection and hearts were harvested after 2 days.
Van Hentenryck M, Li Z, Murphy PM, Czechowicz A (2022) Antibody-based preparative regimens for cell, tissue and organ transplantation. (eds. 162). OBM Transplantation 6(3):162. doi: 10.21926/obm.transplant.2203162
Objective: Provide a review of progress in the use of antibodies to support cell and tissue transplantation with a particular focus on induction of donor-specific tolerance for solid organ transplantation.
Summary: Antibody-based conditioning to prepare the recipient is a promising approach towards achieving transplant tolerance in both hematopoietic and solid organ transplant settings.
Usage: To enhance HSC depletion while avoiding bystander toxicity (neutropenia, lymphopenia, and thrombocytopenia) caused by CD45-radioimmunotherapy, Palchaudhuri et al. developed a saporin-based CD45 (CD45-SAP) immunotoxin using a biotinylated antibody and Streptavidin-ZAP.
Q: Does Mab-ZAP (Cat. #IT-04) bind to the FC portion of mouse IgG?
A: The antibody used to create our Mab-ZAP (IT-04), will react with whole molecule mouse IgG, which includes the Fc portion and the two antigen binding Fab portions.
Q: Can your FabFc-ZAP human (Cat# IT-65) bind to the Fc portion of another species, such as mouse IgG? It looks like it binds to mouse IgG in our assay.
A: The antibody used to create our FabFc-ZAP Human (IT-65), can react with the Fc (gamma) portion of human IgG heavy chain and should not react with the Fab portion of human IgG. However, there could be minimal cross-reaction with mouse, horse, or bovine serum proteins, and it is possible to see cross-reaction with immunoglobulins from other species.
Kim S, Shukla RK, Kim E, Cressman SG, Yu H, Baek A, Choi H, Kim A, Sharma A, Wang Z, Huang CA, Reneau JC, Boyaka PN, Liyanage NPM, Kim S (2022) Comparison of CD3e antibody and CD3e-sZAP immunotoxin treatment in mice identifies szap as the main driver of vascular leakage. Biomedicines 10(6):1221. doi: 10.3390/biomedicines10061221
Objective: Investigate and identify the toxicity profiles of a CD3e-mAb and an immunotoxin of this CD3e antibody conjugated to saporin via a biotin-streptavidin bond, S-CD3e-IT.
Summary: The two agents had opposite effects on T cells, with the antibody alone able to modulate CD3e on the cell surface while the S-CD3e-IT caused depletion of the cell. The immunotoxin increased the infiltration of polymorphonuclear leukocytes (PMNs) into the tissue parenchyma of the spleen and lungs, a sign of vascular permeability while the antibody alone showed no signs of vascular leakage.
Usage: S-CD3e-IT was prepared by reacting biotinylated CD3e antibody with Streptavidin-ZAP in a 1:1 molar ratio. C57BL/6J mice received 25 μg of S-CD3e-IT in sterile 200 μL PBS, twice a day via retro-orbital injection for four days.
Q: Is the dosage of Fab-ZAP always enough for any level of antibody concentration?
A: The 4.5 nM dosage of Fab-ZAP is the recommended concentration. We do not typically see unspecific killing at 4.5 nM on most cell lines. If the concentration of Fab-ZAP is increased, it may undergo bulk-phase endocytosis and kill cells indiscriminately. A lower concentration of Fab-ZAP may lead to antibody competition, resulting in a lack of killing of cells at the highest concentration of antibody.
Q: Each concentration is suggested to perform 6 replications, can it be adjusted more or less in practice?
A: Yes, the assay design is meant to be a thorough approach but can be adjusted by the user. We recommend 6 replications based on our 96-well plate template design. The concentration of Fab-ZAP is 4.5 nM in the suggested protocols.
Q: Can Fab-ZAP detect the targeted antibody still in supernatant?
A: As long as there is nothing in the supernatant inhibiting the reactivity of Fab-ZAP, it should work. We do not typically recommend this, but in theory it should be possible. I would be cautious of this approach based off of the presumed lack of established concentration of antibody.
Q: Instead of performing the reaction between our biotinylated peptide and Streptavidin-ZAP at the initially provided concentration of Strep-ZAP (20 µM), is it OK if the reaction is done at a 10-fold more dilute concentration? This request is to ensure we don’t have any solubility problems with our very tricky lipophilic peptide. Our protocol would be to first dilute Streptavidin-ZAP to 2 µM with PBS and then add the peptide in DMSO (10% final), and store the aliquoted resulting 1.82 µM solution?
A: In regards to your question, while keeping in mind your solubility concerns, we suggest that you:
Proceed with diluting the Streptavidin-ZAP to 2 uM with PBS as you suggest, BUT, only react the amount of Streptavidin-ZAP necessary for the next step.
Store the undiluted and unreacted Streptavidin-ZAP at -80°C until you’re ready for more conjugate.
We understand the solubility of the peptide is a concern, and rightfully so. However, we also do not want to compromise the Streptavidin-ZAP during storage, considering its value.
Q: We have your ZAP internalization kit and I have a question regarding the concentrations used in the cytotoxicity assay. The Hum-ZAP used in the assay (mentioned in the PDF protocol) is 4.5 nM and the target agent was 10 nM to 1 fM. Is there a stoichiometric relation between Hum-ZAP and the target agent concentrations?
A: To answer your question simply, yes, there is a stoichiometric relation between a secondary conjugate and the targeting agent.
Q: If I use higher concentrations of the target antigen, then should I also increase the concentration of Hum-ZAP?
A: It may be intuitive to think that using a higher dose of primary antibody induces a higher amount of cell death, but as seen in the attached figure, at the highest concentration of 192-IgG (10 nM = Log -8) there is a lessened amount of killing, at a 25-fold lower concentration, as compared to the antibody. The explanation for this is that, at the higher concentrations of primary antibody, there is more unconjugated 192-IgG and fewer 192-IgG+Fab-ZAP complexes. The free 192-IgG then out-competes the conjugates for cell surface binding sites which, in turn, decreases the amount of Saporin being internalized, hence less cell death.
Ancheta LR, Shramm PA, Bouajram R, Higgins D, Lappi DA (2022) Saporin as a commercial reagent: its uses and unexpected impacts in the biological sciences-tools from the plant kingdom. Toxins (Basel) 14(3):184. doi: 10.3390/toxins14030184
Hickerson BT, Daniels-Wells TR, Payes C, Clark LE, Candelaria PV, Bailey KW, Sefing EJ, Zink S, Ziegenbein J, Abraham J, Helguera G, Penichet ML, Gowen BB (2022) Host receptor-targeted therapeutic approach to counter pathogenic New World mammarenavirus infections. Nat Commun 13(1):558. doi: 10.1038/s41467-021-27949-3
Objective: Demonstrate that a fusion protein of the antibody (ch128.1/IgG1) directed against the apical domain of human transferrin receptor 1 (hTfR1) and the Machupo virus (MACV) can inhibit infection of attenuated and pathogenic New World mammarenaviruses (NWMs).
Summary: NWMs cause life-threatening hemorrhagic fever (HF) and these viruses enter into cells via hTfR1. Use of ch128.1/IgG1 with other promising direct-acting small molecule antivirals or antibodies targeting the viral envelope glycoprotein would provide a complementary therapeutic strategy that would increase efficacy and reduce the emergence of drug resistance.
Usage: References MonoBiotin-ZAP reacted with avidinylated anti-hTfR (ch128.1Av) in a 1:1 molar ratio on ice for 30 minutes.
Objective: To demonstrate that biotinylated anti-CD45-SAP or anti-cKit-SAP mixed with Streptavidin-Saporin along with Janus kinase 1/2, enables alloengraftment on murine allo-hematopoietic stem cell transplantation (HSCT) models.
Summary: HSCT has therapeutic potential. However, the transplantation requires first depletion and secondly, for allogeneic-HCST, host and immune responses need to be controlled to prevent graft rejection. The allo-HSCT conditioning strategy exemplifies the promise of immunotherapy to improve the safety of HSCT for treating hematologic diseases.
Usage: Antibodies were incubated with Streptavidin-ZAP (1:1 molar ratio) for 15 minutes at 20°C and . The doses of CD45.2 and cKit conjugates were injected retroorbitally (41.8 μg and 33.2 μg, respectively).
Martin Perez C, Conceição M, Raz R, Wood MJA, Roberts TC (2022) Enhancing the therapeutic potential of extracellular vesicles using peptide technology. (eds. Langel Ü). In: Cell Penetrating Peptides. Methods in Molecular Biology 2383:119-141. Humana, New York, NY. doi: 10.1007/978-1-0716-1752-6_8
Objective: To modify EVs with peptides which confer specific advantageous properties, thus enhancing their therapeutic potential.
Summary: The authors provide an overview of the applications of peptide technology with respect to EV therapeutics. We focus on the utility of EV-modifying peptides for the purposes of promoting cargo loading, tissue-targeting and endosomal escape, leading to enhanced delivery of the EV cargo to desired cells/tissues and subcellular target locations. Both endogenous and exogenous methods for modifying EVs with peptides are considered.
Usage: Streptavidin-ZAP is combined with biotinylated peptides to make a targeted saporin conjugate.
Wong JJW, Selbo PK (2021) Light-controlled elimination of PD-L1+ cells. J Photochem Photobiol B 225:112355. doi: 10.1016/j.jphotobiol.2021.112355
Objective: To investigate novel strategies that simultaneously target both tumor cells and immunosuppressive cells in the tumor microenvironment. The focus was on the evaluation in vitro of Anti-PD-L1-SAP combined with photochemical internalization (PCI) as a therapeutic strategy to target and eliminate PD-L1 expressing tumor and immunosuppressive cells.
Summary: The authors show that the intracellular light-controlled drug delivery method induces specific and strongly enhanced cytotoxic effects of Anti-PD-L1-SAP in the PD-L1+ triple-negative breast cancer MDA-MB-231 cell line, while no enhanced efficacy was obtained in the PD-L1 negative control cell line MDA-MB-453.
Usage: Anti-PD-L1-SAP and Streptavidin-ZAP (Control) were used in a cytotoxicity assay.
Lodhi MS, Khan MT, Bukhari SMH, Sabir SH, Samra ZQ, Butt H, Akram MS (2021) Probing transferrin receptor overexpression in gastric cancer mice models. ACS Omega 6(44):29893-29904. doi: 10.1021/acsomega.1c04382
Objective: To investigate the role of the transferrin receptor, a glycoprotein receptor that is expressed many-folds on rapidly growing cells due to the greater demand of iron, in gastric cancer.
Summary: A mouse model of gastric cancer has the potential to be used in the future to study the therapeutic effects of cancer medicines, and overexpression of transferrin receptors could be identified through the designed probe to be used as diagnostics.
Iida K, Abdelhamid Ahmed AH, Nagatsuma AK, Shibutani T, Yasuda S, Kitamura M, Hattori C, Abe M, Hasegawa J, Iguchi T, Karibe T, Nakada T, Inaki K, Kamei R, Abe Y, Nomura T, Andersen JL, Santagata S, Hemming ML, George S, Doi T, Ochiai A, Demetri GD, Agatsuma T (2021) Identification and therapeutic targeting of GPR20, selectively expressed in gastrointestinal stromal tumorswith DS-6157a, a first-in-class antibody-drug conjugate. Cancer Discov 11(6):1508-1523. doi: 10.1158/2159-8290.Cd-20-1434
Objective: Introduce DS-6157a, an anti-GPR20 antibody-drug therapeutic for gastrointestinal stromal tumors (GIST).
Summary: The only approved treatments for GIST are currently tyrosine kinase inhibitors (TKI) which can be problematic. They lead to secondary resistance mutations in KIT or PDGFRA and disease progression. The authors identified G protein-coupled receptor 20 (GPR20) as a non-tyrosine kinase target and assessed its expression in cell lines, xenografts, and clinical samples. Preclinical pharmacokinetics and safety profile support its development as a novel GIST therapy.
Usage: Internalization activity of anti-GPR20 mAbs were evaluated by using Rat-ZAP. GPR20-expressing 293T cells were plated at 2500 cells/well in 96-well plates. Cells were treated with dilutions of various anti-GPR20 and 500 ng/ml of Rat-ZAP for 3 days. The percentage of living cells were measured using a CellTiter-Glo Luminescent Cell Viability Assay.
