kolleamm said:
That would be ideal but how hard would it be to produce such cells even if we knew their exact design?
There are now lots of ways to make antibodies, but they are rather technical and not easy to explain here. Some don't even use immune system cells.
However, getting the specificity for the bad cells and not the good ones will be the problem.
It is possible to sort through many clones of antibody producing cells until you find some with the specificity you want. This is the monoclonal antibody approach.
It would be very unusual to be able to design an antibody from their chemistry up. Without knowing what the antigen is it would be impossible. Immunizations can do this because this is what the immune system does normally.
You need a good screening (or selection) scheme to find the idea antibody producing cells.
This requires the appropriate biological material for immunizing and screening.
kolleamm said:
That would be the most ideal way yes but for that you would need to engineer cells etc...
My solution proposes that we just filter them out somehow with the aid of a centrifuge.
Using a centrifuge in this way will not be an effective treatment for cancer. You would be treating partions of the blood volume as batches. The remaining blood would have un-removed cancer cells and would mix with any of the previously centrifuged blood put back in the patient. The un-removed cancer cells would continue to divide. The population would not be eradicated with this method.
An antibody filtration process (more of a continuous process rather then a batch) is more approachable technically, but would still have problem of filtered and unfiltered blood mixing.
In situ approaches (inside the patient), described by
@DaveE, are being tried out. using antibodies tolabel the cancer cells with either things to kill the cancer cells directly (like toxins or radioactive atoms), or indirectly antibodies carrying other molecules activated by things like light or infrared or possible magnetic fields like in an MRI.
There are probably additional ways to do this.