FAQ
Q: What is the difference between in vivo and in vitro antibody production?
A: Monoclonal antibodies are produced by so-called hybridoma cells. Traditionally hybridoma cells were grown, or cultured, by injecting them to mice peritoneum. In in vivo production cells secrete antibodies to so-called ascites fluid and the antibodies can be purified from this fluid. In in vitro production cells are cultured in on a plate or in a flask or a flowpath using defined cell culture media.
Q: What is the animal source for medixMAB antibodies?
A: All medixMAB antibodies are derived from mice so if a secondary antibody is used rabbit anti-mouse or goat anti-mouse antibody should be used. However, it should be noted that after the hybridoma has been developed no animals are used for production.
Q: What is hollow-fiber technology?
A: In small-scale cell culture the cells are grown on a plate or in a flask. In order to maintain the culture, the medium has to be replaced frequently and usually this is done manually. Hollow-fiber bioreactors employ fibers with small pores that are placed in a shell-and-tube arrangement. The cells are placed into the shell extracapillary space. The oxygen and medium are supplied through the intracapillary fiber lumen. The pores in the fibers are small enough to allow molecules of certain size to enter the extracapillary space, however, cells and monoclonal antibodies are too big to escape from the extracapillary space, and thus they can be collected during the culturing by draining the spent medium from the extracapillary fiber lumen.
Q: What is serum- or protein free cell culture?
A: It is common that mammalian cells are grown in a medium that is supplemented with animal serum. A common supplement is for example fetal calf serum. Serum supplementation has some drawbacks. First of all, animal serums are relatively expensive. Secondly, the content of different animal serums is not defined and thus there can be differences between serum lots and also serums from different manufacturers may be different. Thirdly, serum contains immunoglobulin, which may copurify with the produced monoclonal antibody and these antibodies may cause problems in some applications. Some of our monoclonal antibodies are produced in serum free medium and some are produced in totally protein free medium. Serum free medium contains normal cell medium components and some proteins, but not immunoglobulins. In addition, protein content is extremely low compared to serum-supplemented medium. A protein free culture medium contains only the necessary components required for cell growth, but no proteins.
Q: What is Protein A-affinity chromatography?
A: All our monoclonal antibodies are purified using protein A-affinity chromatography. Protein A is a protein normally found on surface of Staphylococcus aureus. Protein A binds to most mammalian derived immunoglobulins by interacting with the Fc part of the antibody. Protein A-affinity chromatography is a simple and a fast method to obtain pure antibodies with just few steps.
Q: How is the IgG-subclass determined?
A: The subclass of our antibodies is determined using subclass specific antibodies and BIACORE biosensor.
Q: Why are different antibodies in different buffers?
A: Although all antibodies have a similar structure, their biochemical properties may be very different from each other. They have differences in their glycosylation, their isoelectric points are different and all these differences mean that they behave differently in different buffers. During the development phase our R&D tests how antibodies are preserved in different buffers and also how soluble the antibodies are in different buffers. This information is very useful for customer advice on which buffers can be used, and most importantly, which buffers should not be used at all.
Q: Can the antibodies stored in a freezer?
A: Usually we recommend that antibodies should be stored in refrigerator. We do not test systematically how different antibodies behave after freeze thawing and therefore it should always be tested carefully if one wants to store the antibodies in a freezer. Most antibodies can be stored in a freezer but should always be tested case-by-case. Most proteins do not tolerate repeated freeze thawing and this should also be avoided with monoclonal antibodies.
Q: What is BIACORE biosensor?
A: BIACORE biosensor measures protein-protein-interactions in real time using so called surface plasmon resonance method. With this method it is possible to measure affinity constants as well as binding kinetics. BIACORE biosensor is also used to map our antibody pairs to find the most suitable pair for each application. It should be noted that affinity constants measured with BIACORE are usually 10 - 100 fold lower than those measured with traditional RIA/Scatchard plot.
Q: Do we know the exact epitope of the binding site of our antibodies?
A: No. We know the epitope of some antibodies but in most cases we do not. Antibody pairs are however tested with BIACORE and thus we know which antibodies recognize different epitopes and thus which antibodies can be used as pair.
Q: Do our monoclonal antibodies work in all applications?
A: Most of our antibodies may be used in different sandwich-type or rapid test applications. We have not tested them all, in all possible applications, but it is most likely that they do so. We have not tested our antibodies systematically in Western blotting or in immunocytochemistry applications. We know that some of the antibodies work very well in immunoblotting but we cannot guarantee that every antibody does so. Usually monoclonal antibodies work very well in immunocytochemistry applications and thus it is very likely that most antibodies can be used for this also.
Q: If a specific-unspecific antibody pair is used to build up an application which one should be used as a solid phase antibody and which should be used as detecting antibody?
A: It is common to use a specific-unspecific pair in immunoassays. If the pair is used in a traditional sandwich type assay one should use the specific antibody as a solid phase antibody and the unspecific antibody as the detecting antibody. In rapid tests the specific antibody is usually conjugated to latex or gold conjugate and the unspecific antibody is used as a catching antibody.
Q: Can our antibodies be used to make Fab or Fab2-fragments?
A: Yes they can. Using standard methods, it is relatively simple to make these fragments and stability of these fragments in most cases is as good as that of the intact antibody.
Q: How much can we supply?
A: Our production and purification systems are very flexible and we can increase our production to meet the most demanding requirements. Tens or hundreds of grams are not too much.
Q: Can we supply our antibodies even if there is not a distributor in the country?