Monoclonal antibodies development has been limited for a long time to only two species : mice and rats. However, the immune systems of mice and rats are not the most suitable in terms of humoral response to certain antigens, such as human antigens like glucagon. Indeed, the protein sequence of glucagon is the same in mice, rats and human (fig. 1). Small not immunogenic antigens, such as antibiotics or toxins, generally failed to trigger an immune response in such species. This is why some companies have developed fusion cell lines to
generate monoclonal antibodies in rabbit (Abcam-Epitomics) or in sheep (Bioventix). However, these two tools are not totally satisfactory whether in terms of cost, stability or productivity.
SynAbs has therefore opted to develop its own myeloma cell line to manufacture guinea pig monoclonal antibodies and offer more efficient investigation tools for researchers.
The Syn2.2 fusion cell line
After a year of research, SynAbs has managed to develop a fusion cell line, called Syn2.2, so that guinea pig B lymphocytes can be fused efficiently to obtain hybridomas that produce monoclonal antibodies in a stable way (fig. 2). Around 107 splenocytes can be isolated in a guinea pig spleen, a comparable number to rats but around twice that for mice. The Syn2.2 fusion rate with guinea pig splenocytes is comparable to that obtained with SP2O for mice or IR983 for rats, i.e. approximately 12 hybridomas per million fused splenocytes, which means that more than 1000 hybridomas can be obtained from a guinea pig spleen. After analysis, we observed that nearly 50% of the hybridomas produced an antibody,
with production rates comparable to those for mice and rats.
The immune response
It has been observed on many occasions that the humoral response to a particular antigen was on average at least two times higher in guinea pigs than in rats or mice.
For example, here are the humoral responses of a guinea pig (fig. 3a) and a rat (fig. 3b) immunised in the same way with a steroid coupled to KLH and determined by titration on the same steroid coupled to ovalbumin.