Not stupid. NOTE: Not my field, so speaking off basic knowledge here. Happy to be corrected. Tl;dr: because biology at scale is complicated. Longer-form, beca

Not stupid. NOTE: Not my field, so speaking off basic knowledge here. Happy to be corrected. Tl;dr: because biology at scale is complicated. Longer-form, because antibodies and immunological response are somewhat complicated. Knowing what an antibody looks like, how to produce it, and how to scale that production in a safe and reliable way are all very different things. Older article, but general concepts: http://neobiolab.com/research/in-vitro-and-in-vivo-production-of-antibodies http://neobiolab.com/research/in-vitro-and-in-vivo-productio... ... And because the in vivo methods we know of are ethically dicey. To rephrase it in rough terms -- creating custom cancers that produce the thing we want and giving them to mice, then harvesting concentrated antibodies from the tumors. See: https://en.wikipedia.org/wiki/Hybridoma_technology https://en.wikipedia.org/wiki/Hybridoma_technology