Vitamin B12-binders in human body fluids. II. Synthesis in vitro.

Tissue cultures of gastric mucosa, submandibular and parotid glands have been made in medium with amino acids labelled with C. Autoradiographs of immunoelectrophoresis of the culture fluids have shown that vitamin B-binders are synthesized by these tissues. Submandibular and parotid glands synthesized only binder 2. Gastric mucosa synthesized binders 1 and 2. Binder 3 was never synthesized by any of the tissues. The cells responsible for the synthesis of binder 2 are certainly multiple. In salivary glands serous cells, common to submandibular and parotid glands, are probably the originators of binder 2. In gastric mucosa, binder 2 originates either from leucocytes or from gastric cells different from the ones synthesizing binder 1.