Can different brands of fetal bovine serum maintain hybridoma cells at a concentration of 2%?

Short-term amplification at 2%-5% is feasible, but serum should be treated as a lot-sensitive material. Experience shows that hybridomas can be maintained for 72-96 hours at 2%, but different clones vary widely, and one condition cannot be applied to all. When selecting brands, in addition to considering whether they are domestic or imported, it is even more important to look at endotoxin, hemoglobin concentration, and lot-to-lot consistency. Some high-end domestic systems actually perform more stably under low serum than ordinary imported fetal bovine serum. It is recommended to take two existing brands and run four groups at 5% and 2%, with a fixed inoculation density, and record viability, doubling time, and antibody titer at 24, 48, and 72 hours. If viability drops to 70% at 72 hours, first restore it to 5%-7.5%.

Don't focus solely on serum concentration when cutting costs. Although 2% saves serum, it tends to cause viability fluctuations and reduced secretion. For short-term expansion, we use 5% at a seeding density of approximately 5×10^5/ml, which keeps viability stable; 2% is only used for maintenance or short-term culture not exceeding 3 days. With 3-4 bottles per month and a budget of no more than 3000 per bottle, this budget can screen good batches, but the key is to have the supplier provide low-serum culture data or allow testing 2-3 lots first. Hybridomas are highly dependent on hormones and lipids in serum; at low concentrations, it is recommended to add 1× ITS and 1 mM sodium pyruvate, which helps with viability.

Dropping directly from 10% to 2%, viability falling from 90% to 70% is very common, and it's not necessarily a brand issue—more often it's due to adapting too quickly. It is recommended to first drop to 7.5%, stabilize for 3 passages, then drop to 5%, and finally to 2% for short-term expansion. At 2%, the inoculation density must be increased; when viability is low, it is very difficult to rescue. It is best to supplement the basal medium with insulin-transferrin-selenium or serum-free supplement, otherwise the hybridoma's antibody secretion and doubling will be affected. Two domestic brands showed viability drops at 72 hours, indicating that the current batch may not be compatible, but before switching brands, performing gradient adaptation is more practical.