Antigens are proteins that the immune system can recognize. In the lab, recombinant antigens are made in host cells and then purified for use. You often see them in ELISA, diagnostic kits, vaccine research, or when raising antibodies. What matters is specificity and purity if the antigen is clean and well-folded, the test works well and results are more reliable. Also, when antigen batches behave consistently, fewer surprises happen during experiments.
