Studies on the chemical composition and biological properties of transfer factor.

Dialyzable transfer factor (dTF) was fractionated on Sephadex G-10 and G-25 fine columns, and biological activity was found in 3 fractions. One of these, designated VIa, and having a tendency to adsorb to the Sephadex G-10 gel, was shown to have a therapeutic effect on certain immunological diseases. Analysis of this fraction on thin-layer and gas chromatography and with infrared and mass spectroscopy indicated that about half of this fraction was composed of uracil; additional unidentified heterocyclic and aromatic substances were present in this fraction. Adjacent fraction V contained tyrosine and a small polyribonucleotide, and fraction VII hypoxanthine and additional unidentified components. Our results suggest that the therapeutic activity of dTF is not mediated through an immunologically specific informational molecule, but is rather based on non-specific stimulation of the expression of the immune response.