[The preparation and characterization of transfer factor (author's transl)].

A transfer factor (TF) was prepared and characterized from the leucocytes of Mantoux-positiv donors using a variety of techniques. The results allowed the following conclusions: Whilst extraction by dialysis and phenol (without precipitation) led to nearly the same positiv immunological activities, when assayed in the MEM-test, phenol extracts subjected to RNA-precipitation lost considerable activity. The residual activity was associated with the lower molecular fractions, and RNA itself has shown no activity. Residues after leucocyte dialysation have also shown considerable TF-activity when extracted by phenol. It was found that phenol extraction followed by gel filtration allowed recovery of considerable quantities of active TF, confined to several specific filtration fractions. Combination of active and inactive gel filtration fractions suggested that there existed an inhibitory factor within the extracted leucocyte preparations. This modified preparation and purification procedure may allow the preparation of TF for therapeutic purposes.