What does it take for an antibody to become a new cell-identification marker?
Communications Biology 2025 · Abwiz Bio co-authors · antibody clone 4G3
One new antibody turned a marker into a two-colour way to find blood stem cells.
What this means for a campaignThe target was a membrane protein that needed an antibody good enough to sort on, and no such antibody existed. That is the ordinary shape of the problem we solve: a marker is only as useful as the reagent raised against it. Clone 4G3 came from rabbit monoclonal discovery; for targets that resist recombinant expression we pan on cells directly.
Why this is a hard antibody problem
Haematopoietic stem cells are identified today by combinations of surface markers read out by flow cytometry. The panels work, but they are complex, and very few of the molecules used in mouse reporter systems have turned out to be useful for identifying human HSCs. The gap between “this marker works in a mouse reporter” and “this marker works on human cells” is where most candidates die.
Closing that gap requires an antibody against the human orthologue that is specific enough to sort on, and functional on live cells — not merely a Western blot reagent. For a target where no such antibody exists, the biology cannot be tested at all until someone makes one.
What the study established
- In mouse: using a GFP knock-in at the Plxdc2 locus, Plxdc2-GFP proved highly expressed in HSCs. One in 2.8 Plxdc2-GFP-positive CD150-positive cells gave long-term multi-lineage reconstitution in transplantation — a stringent functional readout, not a staining pattern.
- In human: a novel human PLXDC2 antibody was developed for this work. Human PLXDC2-positive HSCs showed higher long-term multilineage reconstitution ability than PLXDC2-negative HSCs in a xenograft model.
- Conclusion: PLXDC2 is a marker relevant to HSC identification across both species — which is precisely what the field had been short of.
What this says about the kind of work we do
Most of our published work is structural — how an antibody recognises a modification, why one clone works in an assay and another does not. This one is different in a way that is worth stating: the deliverable was a working reagent for a target with no prior antibody, used by an independent group to do their own science.
Three things are required for that to succeed, and none of them are affinity numbers. The antibody has to recognise the native protein on live cells, since sorting is the application. It has to be specific enough that a positive gate means something in a rare-population experiment. And it has to be reproducible, because a marker antibody gets used across years and laboratories.
If you are working on a target with no usable commercial antibody — a poorly characterised surface protein, an orthologue nobody covers, a marker you need for sorting rather than blotting — that is the same problem this campaign solved.
Need an antibody to a target nothing commercial covers?
Tell us the target, the species, and the assay it has to work in — flow, sorting, IHC, imaging. A PhD scientist reads it and replies within two business days. No NDA needed to start.
Talk to a scientist →Frequently asked questions
Can you make an antibody for flow cytometry and cell sorting specifically?
Yes, and it should be specified at the start. An antibody that recognises native protein on a live cell surface is a different screening problem from one that works on a denatured blot, and the two are selected for differently.
What if there is no commercial antibody to my target at all?
That is a common starting point for us rather than an obstacle. What matters is whether the antigen can be presented in a form the immune system and the selection can work with — recombinant protein, peptide, or the native molecule on a cell surface.
Can you raise antibodies against both the mouse and human orthologue?
Yes, and it is worth deciding early whether you want two species-specific antibodies or one cross-reactive antibody, because that changes the immunogen and the selection strategy. Cross-species reactivity can also be engineered into an existing clone.
Will the antibody be reproducible over years?
Yes, because we deliver recombinant clones with sequences rather than hybridoma supernatant. A sequence does not drift and does not run out, which is what a marker reagent needs.
Do we own the antibody?
Yes, sequences included, with no downstream royalties in standard scope.
Want this run on your target?
Raising a usable antibody against a cell-surface marker is the campaign behind this work. These are the services that run it.
- Membrane and difficult-antigen discovery — cell-based panning with negative-cell subtraction, for targets that resist recombinant expression
- Rabbit monoclonal discovery (RabWiz™) — high-affinity, high-specificity rabbit mAbs from immune phage libraries
- Functional antibody discovery — when the antibody has to work in a cell assay, not just bind
Every campaign is scoped individually and quoted. Email info@abwizbio.com with your target or lead sequence, or see all 25 publications and the full service menu.